openmp: Allow classes with static members to be mappable

openmp: Allow classes with static members to be mappable

In OpenMP 5.x, static members are supposed to be not a barrier for a class
to be target-mapped. Remove the check for static members inside
cp_omp_mappable_type_1, and adjusts a testcase.

Merged from:
https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591449.html

gcc/cp/ChangeLog:

	* decl2.cc (cp_omp_mappable_type_1): Remove requirement that all
	members must be non-static; remove check for static fields.

gcc/testsuite/ChangeLog:

	* g++.dg/gomp/unmappable-1.C: Adjust testcase.