Add the --with-automake option to AutoRegen.sh and provide the automake

Add the --with-automake option to AutoRegen.sh and provide the automake
version of the configure script. This is an early commit of the automake
support so that automake support can be tested on multiple platforms. Many
additional Makefile.am need to be added to LLVM before this is of any use.
Please wait until automake support is announced on llvmdev list before
using the --with-automake option.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16837 91177308-0d34-0410-b5e6-96231b3b80d8