x86: fix build on non-C locales.

For some locales regex range [a-zA-Z] does not work as it is supposed to.
so we have to use [:alnum:] and [:xdigit:] to make it work as intended.

[1] http://en.wikipedia.org/wiki/Estonian_alphabetSigned-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/vdso/Makefile

@@ -48,7 +48,7 @@ obj-$(VDSO64-y)			+= vdso-syms.lds
 # Match symbols in the DSO that look like VDSO*; produce a file of constants.
 #
 sed-vdsosym := -e 's/^00*/0/' \
-	-e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'
+	-e 's/^\([[:xdigit:]]*\) . \(VDSO[[:alnum:]_]*\)$$/\2 = 0x\1;/p'
 quiet_cmd_vdsosym = VDSOSYM $@
       cmd_vdsosym = $(NM) $< | sed -n $(sed-vdsosym) | LC_ALL=C sort > $@