middle-end/118174 - bogus TER of tailcall

The following avoids applying TER to direct internal functions that
are tailcall since the involved expansion code path doesn't honor
TER constraints.

	PR middle-end/118174
	* tree-outof-ssa.cc (ssa_is_replaceable_p): Exclude tailcalls.

	* gcc.dg/torture/pr118174.c: New testcase.