http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53430
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-05-21 18:20:15 UTC --- On x86_64 GCC defaults to a "multilib" compiler, meaning one that can produce code for both x84_64 and x86 i.e both 64-bit and 32-bit objects. In order to do that it needs 32-bit glibc support, which on F16 is in the glibc-devel.i686 RPM. If you don't want a multilib compiler, i.e. only want to produce 64-bit objects, then build GCC with --disable-multilib
