Log Message:
Apparently, IRIX can do --enable-shared.  However, regardless of what
IRIX system we are on, gcc can NOT be compiled (bootstrapped) as a
64bit binary.  Fortunately, IRIX64 can handle 32bit binaries, so that we
can force use of 32bit when using MIPSPro.

This allows gcc3-c to build fine under IRIX and IRIX64.