[AArch64 costs 4/18] Better estimate cost of building a constant

[AArch64 costs 4/18] Better estimate cost of building a constant

git cherry-pick 3967ee6

gcc/

	* config/aarch64/aarch64.c (aarch64_build_constant): Conditionally
	emit instructions, return number of instructions which would
	be emitted.
	(aarch64_add_constant): Update call to aarch64_build_constant.
	(aarch64_output_mi_thunk): Likewise.
	(aarch64_rtx_costs): Estimate cost of a CONST_INT, cost
	a CONST_DOUBLE.

Change-Id: I3396ecbe27c44603b350efa56021c49373da0e76
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@210496 138bc75d-0d04-0410-961f-82ee72b054a4