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

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

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.

Co-Authored-By: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
From-SVN: r210496