Remove MachineModulePass from LLVM about patmos-llvm HOT 3 OPEN

We cannot trivially move MachineModulePass into the Patmos folder as the serialization pass depends on it.
Serialization is also a customization of the LLVM, which means it must also be moved into the Patmos folder to continue to use MachineModulePass.

We could move the serialization into the Patmos folder, however, it seems that platin also supports ARM targets, which means it might have been the plan to add the serialization to the ARM backend too.

from patmos-llvm.

Serialization is not enabled for the ARM targets, so effectively PML Import/Export is a Patmos specific pass. Will move it into the Patmos folder.

from patmos-llvm.

Moving PML Import/Export into the Patmos folder results in clang failing to build, since it uses the PML.h header.

from patmos-llvm.