[OPENMP50] extend array section for stride (Parsing/Sema/AST)

Reviewers: ABataev, jdoerfert

Reviewed By: ABataev

Subscribers: yaxunl, guansong, arphaman, sstefan1, cfe-commits, sandoval, dreachem

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82800