This patch moves the sqrt and cbrt simplification rules to match.pd.
builtins.c now only does the constant folding.

Bootstrapped & regression-tested on x86_64-linux-gnu.

gcc/
	* builtins.c (fold_builtin_sqrt, fold_builtin_cbrt): Delete.
	(fold_builtin_1): Update accordingly.  Handle constant arguments here.
	* match.pd: Add rules previously handled by fold_builtin_sqrt
	and fold_builtin_cbrt.

gcc/testsuite/
	* gcc.dg/builtins-47.c: Test the optimized dump instead.

From-SVN: r228616