Enabled command line option to link libiomp5.so or libomp.so or libgomp.so libraries using cmake.
Eg:- -DOpenMP_libomp_LIBRARY=<path to openmp library including library name>.
If we not set above variable, by default openmp library will be libomp.so for clang and libgomp.so for gcc compiler.
Change-Id: I5bffa10ff8351f5d10f0d543cbdf55aa16c84c90