Add -Werror-implicit-function-declaration

Add -Werror-implicit-function-declaration
This makes builds fail sooner if something is implicitly defined instead
of having to wait half an hour for it to fail at the linking stage.

Signed-off-by: Dave Jones <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Makefile

@@ -313,7 +313,8 @@ LINUXINCLUDE    := -Iinclude \
 CPPFLAGS        := -D__KERNEL__ $(LINUXINCLUDE)
 
 CFLAGS          := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-                   -fno-strict-aliasing -fno-common
+		   -fno-strict-aliasing -fno-common \
+		   -Werror-implicit-function-declaration
 AFLAGS          := -D__ASSEMBLY__
 
 # Read KERNELRELEASE from include/config/kernel.release (if it exists)