minor documentation issue

[Paul Zimmermann]

       Hi,

on http://gmplib.org/gmp4.2.html, I guess the sentence:

#  Fix problems with x86 --enable-fat, where the compiler where told to
                                                          ^^^^^
   generate code for the build machine, not plain i386 code as it should.

should be corrected into: "... was ...".

Paul Zimmermann