PR116019: Improve tail call error message

PR116019: Improve tail call error message

The "tail call must be the same type" message is common on some
targets with C++, or without optimization. It is generated
when gcc believes there is an access of the return value
after the call. However usually it does not actually corespond
to a type mismatch, but can be caused for other reasons.

Make it slightly more vague to be less misleading.

gcc/ChangeLog:

	PR c++/116019
	* tree-tailcall.cc (find_tail_calls): Change tail call
	error message.