Always include libgfortran.h first; sanitize header dependencies.

Always include libgfortran.h first; sanitize header dependencies.

libgfortran/ChangeLog:

	* nca/coarraynative.c: Do not include util.h. Remove commented
	include for stdlib.h..
	* nca/collective_subroutine.c: Move #include <string.h> after
	other #include statement.
	* nca/hashmap.c: Include shared_memory.h and allocator.h
	* nca/hashmap.h: Remove includess.
	* nca/libcoarraynative.h: Include only those headers which
	are needed.
	* nca/shared_memory.c: Do not include util.h
	* nca/shared_memory.h: Do not include other headers.
	* nca/sync.c: Move include of string.h after other headers.
	* nca/sync.h: Remove include of shared_memory.h and alloc.h.
	* nca/util.h: Do not include stdint.h and stddef.h; include
	limits.h and assert.h.
	* nca/wrapper.c: Remove include for sync.h, util.h and
	collective_subroutine.h. Move include of string.h after other
	headers.