Moved aclocal.m4 to acinclude.m4. To re-generate the configure script,

do the following:
% cd llvm/autoconf
% aclocal
% autoconf -o ../configure

This changes facilitaties the following:
1) It should be easier to incorporate new autoconf macros.
2) It allows for conversion to Automake (should we ever desire it).

llvm-svn: 10655