* builtins.def: Defome atan, atanf, atanl, tan, tanf and tanl
	builtin functions (and their __builtin_* variants).
	* builtins.c (mathfn_built_in): Handle tan{,f,l} and atan{,f,l}.
	(expand_builtin): Don't expand tan{,f,l} or atan{,f,l} when not
	optimizing.

	* doc/extend.texi: Document new tan and atan builtins, and
	their float and long double variants.

	* gcc.dg/builtins-1.c: Add tests for tan and atan.
	* gcc.dg/builtins-4.c: Add test for fmod.

From-SVN: r67137