builtins.c (fold_builtin_cabs): Delete prototype.

	* builtins.c (fold_builtin_cabs): Delete prototype.  Require an
	additional FNDECL argument.  Optimize cabs(-z) and cabs(~z) as
	cabs(z).
	(fold_builtin_decl) <BUILT_IN_CABS>: Update fold_builtin_cabs call.

	* gcc.dg/builtins-54.c: New test case.

From-SVN: r114276