[PATCH] ppc32: biarch gcc support

A native powerpc64-linux gcc can not compile a ppc32 kernel properly.  This
patch fixes it.  It was copied from ppc64.  The change to vmlinux.lds.S
fixes this error:

ld: warning: powerpc:common architecture of input file `init/built-in.o' is
incompatible with powerpc:common64 output
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc/Makefile

@@ -13,6 +13,13 @@
 # This must match PAGE_OFFSET in include/asm-ppc/page.h.
 KERNELLOAD	:= $(CONFIG_KERNEL_START)
 
+HAS_BIARCH	:= $(shell if $(CC) -m32 -S -o /dev/null -xc /dev/null > /dev/null 2>&1; then echo y; else echo n; fi;)
+ifeq ($(HAS_BIARCH),y)
+AS		:= $(AS) -a32
+LD		:= $(LD) -m elf32ppc
+CC		:= $(CC) -m32
+endif
+
 LDFLAGS_vmlinux	:= -Ttext $(KERNELLOAD) -Bstatic
 CPPFLAGS	+= -Iarch/$(ARCH)
 AFLAGS		+= -Iarch/$(ARCH)

arch/ppc/kernel/vmlinux.lds.S

 #include <asm-generic/vmlinux.lds.h>
 
-OUTPUT_ARCH(powerpc)
+OUTPUT_ARCH(powerpc:common)
 jiffies = jiffies_64 + 4;
 SECTIONS
 {