Static inline functions for mallopt helpers

Static inline functions for mallopt helpers

Make mallopt helper functions for each mallopt parameter so that it
can be called consistently in other areas, like setting tunables.

	* malloc/malloc.c (do_set_mallopt_check): New function.
	(do_set_mmap_threshold): Likewise.
	(do_set_mmaps_max): Likewise.
	(do_set_top_pad): Likewise.
	(do_set_perturb_byte): Likewise.
	(do_set_trim_threshold): Likewise.
	(do_set_arena_max): Likewise.
	(do_set_arena_test): Likewise.
	(__libc_mallopt): Use them.