[OpenMP5.0] Allow pointer arithmetic in motion/map clause, by Chi Chun

Chen

Summary:
Base declaration in pointer arithmetic expression is determined by
binary search with type information. Take "int *a, *b; *(a+*b)" as an
example, we determine the base by checking the type of LHS and RHS. In
this case the type of LHS is "int *", the type of RHS is "int",
therefore, we know that we need to visit LHS in order to find base
declaration.

Reviewers: ABataev, jdoerfert

Reviewed By: ABataev

Subscribers: guansong, cfe-commits, sandoval, dreachem

Tags: #clang

Differential Revision: https://reviews.llvm.org/D75077