When the cmake sources are all set to read-only (e.g. after importing into perforce), the CMake.ELF test fails because the copy of the binary is also read-only and cannot be modified. Fix this by copying the binary without source permissions.
This commit adds a CMake.ELF test to exercise cmELF and file(RPATH_*). We test all combinations of 32/64-bit and LSB/MSB binaries.