* builtins.c (CASE_MATHFN_REENT): New macro.
	(mathfn_built_in): Use it.
	* builtins.def (BUILT_IN_GAMMA_R, BUILT_IN_GAMMAF_R,
	BUILT_IN_GAMMAL_R, BUILT_IN_LGAMMA_R, BUILT_IN_LGAMMAF_R,
	BUILT_IN_LGAMMAL_R): New.
	* doc/extend.texi: Document new builtins.

testsuite:
	* gcc.dg/builtins-1.c: Test reentrant gamma functions.

From-SVN: r124821