[PATCH] Makefile: Improve compiler header dependency check

[David Aguilar <davvid@gmail.com>]

The Makefile enables CHECK_HEADER_DEPENDENCIES when the
compiler supports generating header dependencies.
Make the check use the same flags as the invocation
to avoid a false positive when user-configured compiler
flags contain incompatible options.

Signed-off-by: David Aguilar <davvid@gmail.com>
---
I fired up git's next branch on a mac laptop where I
have a config.mak that builds universal git binaries:

CFLAGS = -arch i386 -arch x86_64

This configuration broke when 111ee18c31f9bac9436426399355facc79238566
was merged into next.  gcc cannot generate header dependencies when
multiple -arch statements are used but the test generated a false
positive.

 Makefile |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index aa67142..30f3812 100644
--- a/Makefile
+++ b/Makefile
@@ -1251,7 +1251,8 @@ USE_COMPUTED_HEADER_DEPENDENCIES =
 else
 ifndef COMPUTE_HEADER_DEPENDENCIES
 dep_check = $(shell sh -c \
-	'$(CC) -c -MF /dev/null -MMD -MP -x c /dev/null -o /dev/null 2>&1; \
+	'$(CC) -c -MF /dev/null -MMD -MP -x c /dev/null -o /dev/null \
+	$(ALL_CFLAGS) $(EXTRA_CPPFLAGS) 2>&1; \
 	echo $$?')
 ifeq ($(dep_check),0)
 COMPUTE_HEADER_DEPENDENCIES=YesPlease
-- 
1.7.6.476.g57292