Code improvements in OpenMP CodeGen.
This patch makes class OMPPrivateScope a common class for all private variables. Reworked processing of firstprivate variables (now it is based on OMPPrivateScope too).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219486 91177308-0d34-0410-b5e6-96231b3b80d8