x86: fix build on some non-C locales[1].

For some locales regex range [a-zA-Z] does not work as it is supposed to 
so we have to specify LANG=C to make it work as intended.

[1] http://en.wikipedia.org/wiki/Estonian_alphabet

Signed-off-by: Priit Laes <plaes@plaes.org>

diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index f385a4b..c58e7b9 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -50,7 +50,8 @@ obj-$(VDSO64-y)			+= vdso-syms.lds
 sed-vdsosym := -e 's/^00*/0/' \
 	-e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'
 quiet_cmd_vdsosym = VDSOSYM $@
-      cmd_vdsosym = $(NM) $< | sed -n $(sed-vdsosym) | LC_ALL=C sort > $@
+      cmd_vdsosym = $(NM) $< | LC_ALL=C sed -n $(sed-vdsosym) \
+	  		| LC_ALL=C sort > $@
 
 $(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
 	$(call if_changed,vdsosym)