* 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
