Remove source transformation support

This change removes support for the "source" mode of offline compilation
which is commented with "to be removed in the future as we will use
offline compiler here".

The "source" mode allowed for the CL source to be transformed by
build_script_source.py and then passed to clCreateProgramWithSource(),
and appears to have been developed only for the purpose of testing the
offline compilation infrastructure.

test_common/harness/parseParameters.h

@@ -27,7 +27,6 @@ extern std::string gSpirVPath;
 enum OfflineCompilerOutputType
 {
     kBinary = 0,
-    kSource,
     kSpir_v
 };