[PATCH] x86_64: Pass -32 to the assembler when compiling the 32bit vsyscall pages

This quietens warnings and actually fixes a bug. The unwind tables would
come out wrong without -32, causing pthread cancellation during them
to crash in the gcc runtime.

The problem seems to only happen with newer binutils
(it doesn't happen with 2.16.91.0.2 but happens wit 2.16.91.0.5)

Thanks to Brian Baker @ HP for test case and initial analysis.

Cc: brian.b@hp.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86_64/ia32/Makefile

@@ -27,5 +27,5 @@ $(obj)/vsyscall-sysenter.so $(obj)/vsyscall-syscall.so: \
 $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
 	$(call if_changed,syscall)
 
-AFLAGS_vsyscall-sysenter.o = -m32
-AFLAGS_vsyscall-syscall.o = -m32
+AFLAGS_vsyscall-sysenter.o = -m32 -Wa,-32
+AFLAGS_vsyscall-syscall.o = -m32 -Wa,-32