Update build-many-glibcs.py for binutils ia64 obsoletion.

Update build-many-glibcs.py for binutils ia64 obsoletion.

Since binutils has obsoleted ia64 support, use --enable-obsolete for
now when configuring binutils for ia64 in build-many-glibcs.py (which
requires adding support for architecture-specific binutils configure
options there).  As with other obsoletions, the removal of support for
ia64 in any of (binutils, GCC, Linux kernel) should imply its removal
from glibc.

Tested with build-many-glibcs.py for ia64-linux-gnu (compilers and
glibcs build).