[OPENMP] Fix crash for 'schedule|dist_schedule' clauses during

instantiation.

Added checks for non-dependent context when trygin to capture
non-constant schedule chunk expression for proper codegen of outlined
functions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@272775 91177308-0d34-0410-b5e6-96231b3b80d8