GMP treats pentium3 as i686, refuses to select mpn/x86/p6/p3mmx

[buport at figpost.com]

Hi,

This problem shows up when configuring gmp 4.2.2. Even when I explicitly
say "./configure --build=pentium3-pc-linux-gnu", the configure script
chooses i686 as the CPU type. The culprit is the line:

ac_cv_host=`$ac_config_sub $ac_cv_host_alias`

in the configure script, which runs config.sub to "canonicalize" the host
type. Unfortunately, config.sub turns "pentium3" into "i686". As a result,
the specialized code in mpn/x86/p6/p3mmx never gets selected, and we build
only the generic p6 code instead.

As a separate problem, config.guess does not have a special case for the
Pentium3 either. It outputs "i686-pc-linux-gnu" even if the machine has a
Pentium3 processor.