[CMake] External project and patch files

[Hugh Sorby]

Hello All,

I am using external project to well build some external projects.  I
also patch these projects to play nice for me.  For this I use the
ExternalProject_Add PATCH_COMMAND.  Right now I have two difficulties.

1. I have to combine all my fixes into one patch.  I would prefer to
have a list of patches so that I can make it clearer to other developers
what is going to be changed.  This would make it easier to review
patches and view particular mods.

2. When I make changes to a patch and I recompile my external project,
or the build tree holding the external project it doesn't rebuild the
project.  I would be happy with being able to force a clean and rebuild
here for the external project effected.

Has anybody resolved these issues?

Cheers,
Hugh.