Removing the Makefile/Perl build system.

This change deletes the Makefile+Perl build system and all files used by it
which aren't used by the CMake build system. This included many Perl files,
*.mk files, iomp* files.  This change also updates the README's and
index.html to instruct the user to use the CMake build system. All mentioning
of the Perl+Makefile based system are removed.

Differential Revision: http://reviews.llvm.org/D12331

llvm-svn: 247583