[OPENMP]Fix PR45383: type dependent array subscripts are diagnosed erroneously.

Summary:
If the array subscript expression is type depent, its analysis must be
delayed before its instantiation.

Reviewers: jdoerfert

Subscribers: yaxunl, guansong, caomhin, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78637