Configure fails on 32-bit platform

[Jeffrey Walton]

Hi Everyone,

Configure seems to be misdetecting this 32-bit platform. The machine
is CentOS 6, i686 .

The environment is:

    PKG_CONFIG+PATH: /usr/local/lib/pkgconfig
     CPPFLAGS: -I/usr/local/include -DNDEBUG
       CFLAGS: -g2 -O2 -m32 -march=native -fPIC
     CXXFLAGS: -g2 -O2 -m32 -march=native -fPIC
      LDFLAGS: -L/usr/local/lib -m32 -Wl,-R,/usr/local/lib
-Wl,--enable-new-dtags
       LDLIBS: -ldl -lpthread

 Then:

    $ ./configure
    ...

    configure: error: Oops, mp_limb_t is 32 bits, but the assembler code
    in this configuration expects 64 bits.
    You appear to have set $CFLAGS, perhaps you also need to tell GMP the
    intended ABI, see "ABI and ISA" in the manual.

    $ uname -a
    Linux localhost.localdomain 2.6.32-696.20.1.el6.i686 #1 SMP Fri
Jan 26 18:13:32 UTC 2018 i686 i686 i386 GNU/Linux

Jeff