Disable "maybe-uninitialized" warning globally

Several build configurations had already disabled this warning because
it generates a lot of false positives.  But some had not, and it was
still enabled for "allmodconfig" builds, for example.

Looking at the warnings produced, every single one I looked at was a
false positive, and the warnings are frequent enough (and big enough)
that they can easily hide real problems that you don't notice in the
noise generated by -Wmaybe-uninitialized.

The warning is good in theory, but this is a classic case of a warning
that causes more problems than the warning can solve.

If gcc gets better at avoiding false positives, we may be able to
re-enable this warning.  But as is, we're better off without it, and I
want to be able to see the *real* warnings.

Change-Id: Ie810d255be8911c413c9abe6965a9a66639a1dce
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Makefile

@@ -562,6 +562,8 @@ endif # $(dot-config)
 # Defaults to vmlinux, but the arch makefile usually adds further targets
 all: vmlinux
 
+KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,)
+
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 KBUILD_CFLAGS	+= -Os $(call cc-disable-warning,maybe-uninitialized,)
 else

drivers/staging/prima/Kbuild

@@ -628,7 +628,7 @@ CDEFINES += -DWLAN_OPEN_SOURCE
 endif
 
 # Fix build for GCC 4.7
-EXTRA_CFLAGS += -Wno-maybe-uninitialized -Wno-unused-function
+EXTRA_CFLAGS += -Wno-unused-function
 
 KBUILD_CPPFLAGS += $(CDEFINES)