This patch extends fold_const_call so that it can handle internal
as well as built-in functions.

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

gcc/
	* fold-const-call.h (fold_const_call): Replace built_in_function
	arguments with combined_fn arguments.
	* fold-const-call.c: Include case-cfn-macros.h.
	(fold_const_call_ss, fold_const_call_cs, fold_const_call_sc)
	(fold_const_call_cc, fold_const_call_sss, fold_const_call_ccc)
	(fold_const_call_ssss, fold_const_call_1, fold_const_call): Replace
	built_in_function arguments with combined_fn arguments.
	* builtins.c (fold_builtin_sincos, fold_builtin_1, fold_builtin_2)
	(fold_builtin_3): Update calls to fold_const_call.

From-SVN: r230477