* tree-tailcall.c (pass_tail_recursion): Use gate_tail_calls too.

testsuite/
	* gcc.dg/sibcall-7.c: New test.
	* gcc.dg/tree-ssa/tailrecursion-1.c: Pass -foptimize-sibling-calls.
	* gcc.dg/tree-ssa/tailrecursion-2.c: Likewise.
	* gcc.dg/tree-ssa/tailrecursion-3.c: Likewise.
	* gcc.dg/tree-ssa/tailrecursion-4.c: Likewise.
	* gcc.dg/tree-ssa/tailrecursion-5.c: Likewise.

From-SVN: r113200