Add checksum support for CMakeList generation

We now embed a checksum in the generated CMakeLists.txt files.
The emulators cmake build system will use this to make sure the
makefiles have not changed.

Changing the makefiles without regenerating the CMakeLists.txt will
result in a build break in the emulator.

Change-Id: I242dd3292b0d876d80d92cd36bdbe62c6197d259