Add patch level to llvm version in CMake and Autoconf

The shared library generated by autoconf will now be called
libLLVM-$(VERSION_MAJOR).$(VERSION_MINOR).$(VERSION_PATCH)$(VERSION_SUFFIX).so
and a symlink named
libLLVM-$(VERSION_MAJOR).$(VERSION_MINOR)$(VERSION_SUFFIX).so will
also be created in the install directory.

llvm-svn: 202720