Another patch to extend uses of built_in_function to combined_fn, this time
in tree-ssa-math-opts.c.

Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.

gcc/
	* tree-ssa-math-opts.c: Include case-cfn-macros.h.
	(execute_cse_sincos_1): Use combined_fn instead of built-in codes.
	(pass_cse_sincos::execute): Likewise.

From-SVN: r230481