[OPENMP]Fix PR48076: mapping of data member pointer.

If the data member pointer is mapped, the compiler tries to optimize the
mapping of such data by discarding explicit mapping flags and trying to
emit combined data instead. In some cases, this optimization is not
quite correctly implemented and it leads to a program crash at the
runtime. Instead, if the data member is mapped, just emit it as is and
do not emit combined mapping flags for it.

Differential Revision: https://reviews.llvm.org/D91552