[PATCH] ppc64: override command line AS/LD/CC variables when adding -m64 and co for biarch compilers

The following kind of calls currently fails :

  make ARCH=ppc64 CC="gcc-3.4"

Since the code for detecting a biarch compiler and adding the needed 64bit
magic argument fails if the AS/LD/CC commands are overriden in the command
line.

The attached patch fixes this by using the make override and += directive,
but i am not 100% sure this will work without gmake, as i am no Makefile
expert.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/Makefile

@@ -35,9 +35,9 @@ CROSS32AS	:= $(AS) -a32
 CROSS32LD	:= $(LD) -m elf32ppc
 CROSS32OBJCOPY	:= $(OBJCOPY)
 endif
-AS              := $(AS) -a64
-LD              := $(LD) -m elf64ppc
-CC		:= $(CC) -m64
+override AS	+= -a64
+override LD	+= -m elf64ppc
+override CC	+= -m64
 endif
 
 export CROSS32CC CROSS32AS CROSS32LD CROSS32OBJCOPY