[OpenMP 5.0] - Extend defaultmap, by Chi Chun Chen.

Summary:
For the extended defaultmap, most of the work is inside sema.
The only difference for codegen is to set different initial
maptype for different implicit-behavior.

Reviewers: jdoerfert, ABataev

Reviewed By: ABataev

Subscribers: dreachem, sandoval, cfe-commits

Tags: #clang, #openmp

Differential Revision: https://reviews.llvm.org/D69204