glibc: added workaround for failing builds when building i686 targets

Note:

The actual build error without this workaround:
-----------------------------------------------------------------------------
../sysdeps/i386/i686/multiarch/strcmp.S: Assembler messages:
../sysdeps/i386/i686/multiarch/strcmp.S:90: Error: can't resolve `.text' {.text section} - `strcmp' {.text section}
make[2]: *** [glibc-2.14.1/objdir-i686-unknown-linux-gnu/string/strcmp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
../sysdeps/i386/i686/multiarch/strcspn.S: Assembler messages:
../sysdeps/i386/i686/multiarch/strcspn.S:87: Error: can't resolve `.text' {.text section} - `strcspn' {.text section}
make[2]: *** [glibc-2.14.1/objdir-i686-unknown-linux-gnu/string/strcspn.o] Error 1
-----------------------------------------------------------------------------

The workaround is to disable to build single DSO with optimizations for
multiple architectures.

base/glibc/glibc.conf

@@ -265,3 +265,8 @@ fi
 hook_add prepatch 3 "glibc_prepatch"
 hook_add postmake 5 "glibc_postmake"
 
+# workaround for failing builds when building for i686 cpu family
+case $arch_machine in
+	i686) var_append extraconfopt ' ' "--disable-multi-arch" ;;
+esac
+