PATCH: Configure x86_64 in sysdeps/x86_64/preconfigure

[Roland McGrath]

> $CC may not compile in -mx32 mode by default.  But we can set -mx32 in CFLAGS.

The usual procedure for ABI-changing options is to put them into CC, not
into CFLAGS.  That's how one normally builds for i686 on an x86_64 host,
for example (CC='gcc -m32').  This lets the usual logic for default CFLAGS
take effect, rather than forcing you to adding -g -O2 when all you wanted
to do was add -mx32.


Thanks,
Roland