BGE: Removing the source files for the PHY interfaces since they just contained virtual destructors. This means we had license and doc blocks for 3 lines of code, which seemed silly. This also means that ge_phys_common no longer needs to be built as a library. I tested this with CMake and SCons using GCC; hopefully this doesn't break other systems.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54807 954f8c5b-7b00-dc11-b283-0030488c597c