Semantic checks for the following OpenMP 4.5 clauses.
1. 2.15.4.2 - Copyprivate clause
2. 2.15.3.4 - Firstprivate clause
3. 2.15.3.5 - Lastprivate clause
Add related test cases and resolve test cases marked as XFAIL.
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D91920
Praveen