PR middle-end/30250
	* builtins.c (do_mpfr_lgamma_r): New.
	(fold_builtin_2): Handle builtin gamma_r/lgamma_r.
	* tree.h (CASE_FLT_FN_REENT): New.

testsuite:
	* gcc.dg/torture/builtin-math-2.c: Add gamma_r/lgamma_r tests.
	* gcc.dg/torture/builtin-math-4.c: Likewise.

From-SVN: r124849