openmp: Add support for HBW or large capacity or interleaved memory through the libme...

openmp: Add support for HBW or large capacity or interleaved memory through the libmemkind.so library

This patch adds support for dlopening libmemkind.so on Linux and uses it
for some kinds of allocations (but not yet e.g. pinned memory).

2022-06-09  Jakub Jelinek  <jakub@redhat.com>

	* allocator.c: Include dlfcn.h if LIBGOMP_USE_MEMKIND is defined.
	(enum gomp_memkind_kind): New type.
	(struct omp_allocator_data): Add memkind field if LIBGOMP_USE_MEMKIND
	is defined.
	(struct gomp_memkind_data): New type.
	(memkind_data, memkind_data_once): New variables.
	(gomp_init_memkind, gomp_get_memkind): New functions.
	(omp_init_allocator): Initialize data.memkind, don't fail for
	omp_high_bw_mem_space if libmemkind supports it.
	(omp_aligned_alloc, omp_free, omp_aligned_calloc, omp_realloc): Add
	memkind support of LIBGOMP_USE_MEMKIND is defined.
	* config/linux/allocator.c: New file.