re PR tree-optimization/68501 (sqrt builtin is not used anymore)

re PR tree-optimization/68501 (sqrt builtin is not used anymore)

	PR tree-optimization/68501
	* target.def (builtin_reciprocal): Replace the 3 arguments with
	a gcall * one, adjust description.
	* targhooks.h (default_builtin_reciprocal): Replace the 3 arguments
	with a gcall * one.
	* targhooks.c (default_builtin_reciprocal): Likewise.
	* tree-ssa-math-opts.c (pass_cse_reciprocals::execute): Use
	targetm.builtin_reciprocal even on internal functions, adjust
	the arguments and allow replacing an internal function with normal
	built-in.
	* config/i386/i386.c (ix86_builtin_reciprocal): Replace the 3 arguments
	with a gcall * one.  Handle internal fns too.
	* config/rs6000/rs6000.c (rs6000_builtin_reciprocal): Likewise.
	* config/aarch64/aarch64.c (aarch64_builtin_reciprocal): Likewise.
	* doc/tm.texi (builtin_reciprocal): Document.

From-SVN: r231075