Appending to CFLAGS from configure.ac like this was too naive, passing
custom CFLAGS in make arguments overwrites it. Extend AM_CFLAGS instead.

Fixes: 64c07e38f0494 ("table: Embed creating nft version into userdata")
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 Makefile.am  | 2 ++
 configure.ac | 1 -
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index 5190a49ae69f1..3e3f1e61092bb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -156,6 +156,8 @@ AM_CFLAGS = \
 	\
 	$(GCC_FVISIBILITY_HIDDEN) \
 	\
+	-DMAKE_STAMP=$(MAKE_STAMP) \
+	\
 	$(NULL)
 
 AM_YFLAGS = -d -Wno-yacc
diff --git a/configure.ac b/configure.ac
index da16a6e257c91..3517ea041f7ea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -153,7 +153,6 @@ AC_CONFIG_COMMANDS([nftversion.h], [
 # Current date should be fetched exactly once per build,
 # so have 'make' call date and pass the value to every 'gcc' call
 AC_SUBST([MAKE_STAMP], ["\$(shell date +%s)"])
-CFLAGS="${CFLAGS} -DMAKE_STAMP=\${MAKE_STAMP}"
 
 AC_CONFIG_FILES([					\
 		Makefile				\
-- 
2.51.0