PATCH: Use x86_64 bits/mman.h for both i386 and x86_64

[Roland McGrath]

I concur with Joseph's comments about pointing out any and all API
differences for i386 introduced by the unification.  

Many people nowadays are using -m32 on an x86_64 installation for i386
builds, so if these were real problems they probably would have been
noticed.  But the principle is sound and important regardless.

It looks like an i386 kernel will just ignore MAP_32BIT if an application
were to use it.  So I think it is harmless enough and so the change is fine
as it is.


Thanks,
Roland