Fix assert during the call to getCanonicalDecl.

https://github.com/llvm/llvm-project/issues/56884

The root problem is in isOpenMPRebuildMemberExpr, it is only need to rebuild
for field expression.  No need for member function call.

The fix is to check field for member expression and skip rebuild for member
function call.

Differential Revision: https://reviews.llvm.org/D131024