Only set WARNS if not defined

This would allow interested parties to do experimental runs with an
environment set appropriately to raise all the warnings throughout the
build; e.g. env WARNS=6 NO_WERROR=yes buildworld.

Not currently touching the numerous instances in ^/tools.

MFC after:	1 week

19 files changed, 19 insertions, 19 deletions

diff --git a/lib/libc++/Makefile b/lib/libc++/Makefile
index 330ffaaed9cb..bfb394fda2fb 100644
--- a/lib/libc++/Makefile
+++ b/lib/libc++/Makefile
@@ -71,7 +71,7 @@ cxxrt_${_S}: ${_LIBCXXRTDIR}/${_S} .NOMETA
 	ln -sf ${.ALLSRC} ${.TARGET}
 .endfor
 
-WARNS=		0
+WARNS?=		0
 CFLAGS+=	-isystem ${HDRDIR}
 CFLAGS+=	-isystem ${_LIBCXXRTDIR}
 CFLAGS+=	-nostdinc++
diff --git a/lib/libcxxrt/Makefile b/lib/libcxxrt/Makefile
index 8480cad42674..16847f2ddb28 100644
--- a/lib/libcxxrt/Makefile
+++ b/lib/libcxxrt/Makefile
@@ -20,7 +20,7 @@ SRCS+=		libelftc_dem_gnu3.c\
 		typeinfo.cc\
 		guard.cc
 
-WARNS=		0
+WARNS?=		0
 CFLAGS+=	-isystem ${SRCDIR} -nostdinc++
 CXXSTD?=	c++14
 VERSION_MAP=	${.CURDIR}/Version.map
diff --git a/lib/libopenbsd/Makefile b/lib/libopenbsd/Makefile
index 7b0f3778046c..267d9ceca279 100644
--- a/lib/libopenbsd/Makefile
+++ b/lib/libopenbsd/Makefile
@@ -15,6 +15,6 @@ INTERNALLIB=
 
 CFLAGS+= -I${.CURDIR}
 
-WARNS=	3
+WARNS?=	3
 
 .include <bsd.lib.mk>
diff --git a/lib/libsqlite3/Makefile b/lib/libsqlite3/Makefile
index fc3dc624409f..458e7d7ddfb1 100644
--- a/lib/libsqlite3/Makefile
+++ b/lib/libsqlite3/Makefile
@@ -12,7 +12,7 @@ INCS=	sqlite3.h sqlite3ext.h
 SQLITE=	${SRCTOP}/contrib/sqlite3
 .PATH:	${SQLITE}
 
-WARNS=	3
+WARNS?=	3
 CFLAGS+=	-I${SQLITE} \
 		-DUSE_PREAD=1 \
 		-DSTDC_HEADERS=1 \
diff --git a/lib/libucl/Makefile b/lib/libucl/Makefile
index 3624e3121d1e..15632810277e 100644
--- a/lib/libucl/Makefile
+++ b/lib/libucl/Makefile
@@ -23,7 +23,7 @@ SRCS=		ucl_emitter_streamline.c \
 INCS=		ucl.h
 LIBADD=		m
 
-WARNS=		1
+WARNS?=		1
 CFLAGS+=	-I${LIBUCL_DIR}/include \
 		-I${LIBUCL_DIR}/src \
 		-I${LIBUCL_DIR}/uthash \
diff --git a/lib/libzstd/Makefile b/lib/libzstd/Makefile
index 61369950d504..164156c2c83d 100644
--- a/lib/libzstd/Makefile
+++ b/lib/libzstd/Makefile
@@ -33,7 +33,7 @@ SRCS=	entropy_common.c \
 	debug.c \
 	hist.c \
 	fastcover.c
-WARNS=	2
+WARNS?=	2
 INCS=	zstd.h
 CFLAGS+=	-I${ZSTDDIR}/lib -I${ZSTDDIR}/lib/common -DXXH_NAMESPACE=ZSTD_ \
 		-DZSTD_MULTITHREAD=1
diff --git a/libexec/dma/dma-mbox-create/Makefile b/libexec/dma/dma-mbox-create/Makefile
index a745f591c776..16b03b956f3c 100644
--- a/libexec/dma/dma-mbox-create/Makefile
+++ b/libexec/dma/dma-mbox-create/Makefile
@@ -2,7 +2,7 @@
 
 MAN=
 
-WARNS=	2
+WARNS?=	2
 
 PROG=	dma-mbox-create
 BINMODE=	4554
diff --git a/libexec/dma/dmagent/Makefile b/libexec/dma/dmagent/Makefile
index 187517736e62..f7f127cf4e7e 100644
--- a/libexec/dma/dmagent/Makefile
+++ b/libexec/dma/dmagent/Makefile
@@ -35,7 +35,7 @@ BINMODE=	2555
 .include <bsd.compiler.mk>
 
 .if ${COMPILER_TYPE} == gcc
-WARNS=	5
+WARNS?=	5
 .endif
 
 .include <bsd.prog.mk>
diff --git a/sbin/gvinum/Makefile b/sbin/gvinum/Makefile
index 4caa775be2e1..18550053228a 100644
--- a/sbin/gvinum/Makefile
+++ b/sbin/gvinum/Makefile
@@ -5,7 +5,7 @@ PROG=	gvinum
 SRCS=	gvinum.c gvinum.h geom_vinum_share.c
 MAN=	gvinum.8
 
-WARNS=		2
+WARNS?=		2
 CFLAGS+=	-I${SRCTOP}/sys -I${SYSROOT:U${DESTDIR}}/${INCLUDEDIR}/edit
 
 LIBADD=	edit geom
diff --git a/sbin/tunefs/Makefile b/sbin/tunefs/Makefile
index 7f903b2ef21a..9d0754edca89 100644
--- a/sbin/tunefs/Makefile
+++ b/sbin/tunefs/Makefile
@@ -11,6 +11,6 @@ MOUNT=	${SRCTOP}/sbin/mount
 CFLAGS+=	-I${MOUNT}
 .PATH:	${MOUNT}
 
-WARNS=	3
+WARNS?=	3
 
 .include <bsd.prog.mk>
diff --git a/stand/efi/boot1/Makefile b/stand/efi/boot1/Makefile
index b8644ace4d44..0cad67d21050 100644
--- a/stand/efi/boot1/Makefile
+++ b/stand/efi/boot1/Makefile
@@ -5,7 +5,7 @@
 BOOT1?=		boot1
 PROG=		${BOOT1}.sym
 INTERNALPROG=
-WARNS=		6
+WARNS?=		6
 
 CFLAGS+=	-DEFI_BOOT1
 # We implement a slightly non-standard %S in that it always takes a
diff --git a/stand/efi/gptboot/Makefile b/stand/efi/gptboot/Makefile
index ba0df4ebeeeb..7d6dee85f93f 100644
--- a/stand/efi/gptboot/Makefile
+++ b/stand/efi/gptboot/Makefile
@@ -13,5 +13,5 @@ CFLAGS+=	-DBOOTPROG=\"gptboot.efi\"
 CFLAGS+=	-DHAVE_MEMCPY -I${SRCTOP}/sys/contrib/zlib
 SRCS+=		gpt.c
 CWARNFLAGS.gpt.c+=	-Wno-sign-compare -Wno-cast-align
-WARNS=6
+WARNS?=6
 .include "${.CURDIR}/../boot1/Makefile"
diff --git a/stand/liblua/Makefile b/stand/liblua/Makefile
index 9693f579f801..0f4047769b77 100644
--- a/stand/liblua/Makefile
+++ b/stand/liblua/Makefile
@@ -28,7 +28,7 @@ SRCS+=	lerrno.c lstd.c lutils.c
 .PATH:	${FLUASRC}/modules
 SRCS+=	lfs.c
 
-WARNS=	3
+WARNS?=	3
 
 CFLAGS+= -DLUA_PATH=\"${LUAPATH}\" -DLUA_PATH_DEFAULT=\"${LUAPATH}/\?.lua\"
 CFLAGS+= -ffreestanding -nostdlib -DLUA_USE_POSIX
diff --git a/usr.bin/bmake/Makefile.inc b/usr.bin/bmake/Makefile.inc
index 3cd2872f1530..96431c19d2af 100644
--- a/usr.bin/bmake/Makefile.inc
+++ b/usr.bin/bmake/Makefile.inc
@@ -22,7 +22,7 @@ NO_SHARED?=     YES
 SUBDIR+= tests
 .endif
 
-WARNS=3
+WARNS?=3
 CFLAGS+= -DNO_PWD_OVERRIDE
 
 .if make(after-import)
diff --git a/usr.bin/localedef/Makefile b/usr.bin/localedef/Makefile
index 5b9bcc3b4898..76814dc6e61f 100644
--- a/usr.bin/localedef/Makefile
+++ b/usr.bin/localedef/Makefile
@@ -13,7 +13,7 @@ SRCS=	charmap.c \
 	time.c \
 	wide.c
 
-WARNS=	3
+WARNS?=	3
 ${SRCS:M*.c}: parser.h
 parser.h: parser.y
 
diff --git a/usr.bin/m4/Makefile b/usr.bin/m4/Makefile
index b9d89bd20dab..25c83c093f5f 100644
--- a/usr.bin/m4/Makefile
+++ b/usr.bin/m4/Makefile
@@ -22,7 +22,7 @@ SRCS+=	tokenizer.l
 .endif
 
 GENFILES=	tokenizer.c parser.c parser.h
-WARNS=	3
+WARNS?=	3
 
 tokenizer.o: parser.h
 
diff --git a/usr.bin/users/Makefile b/usr.bin/users/Makefile
index dd04a112b2a8..ba990f890717 100644
--- a/usr.bin/users/Makefile
+++ b/usr.bin/users/Makefile
@@ -1,7 +1,7 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/6/93
 # $FreeBSD$
 
-WARNS=		3
+WARNS?=		3
 PROG_CXX=	users
 CXXFLAGS+=	-fno-rtti
 
diff --git a/usr.bin/zstd/Makefile b/usr.bin/zstd/Makefile
index 40f93d1198a2..797558940c36 100644
--- a/usr.bin/zstd/Makefile
+++ b/usr.bin/zstd/Makefile
@@ -26,7 +26,7 @@ MLINKS=	zstd.1 unzstd.1 \
 	zstd.1 zstdcat.1 \
 	zstd.1 zstdmt.1
 
-WARNS=	2
+WARNS?=	2
 LIBADD=	zstd
 .PATH: ${SRCTOP}/sys/contrib/zstd/programs
 
diff --git a/usr.sbin/ypldap/Makefile b/usr.sbin/ypldap/Makefile
index 7fbe945aaf5d..5c909e3d79fe 100644
--- a/usr.sbin/ypldap/Makefile
+++ b/usr.sbin/ypldap/Makefile
@@ -15,6 +15,6 @@ CFLAGS+=-I${.CURDIR}
 CFLAGS+=-I${SRCTOP}/contrib/pf/libevent
 CFLAGS+=-I${SRCTOP}/lib/libopenbsd
 
-WARNS=	2
+WARNS?=	2
 
 .include <bsd.prog.mk>