SILVerifier: don't enforce that there must be an unreachable after a no-return apply.

This condition does not hold after each pass. It's only the case after running some cleanup-passes.
This verifier condition makes it impossible to bisect the optimization passes.

Author: eeckstein

lib/SIL/Verifier/SILVerifier.cpp

@@ -1504,14 +1504,6 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
             "cannot call coroutine with normal apply");
     require(!calleeConv.funcTy->isAsync() || AI->getFunction()->isAsync(),
             "cannot call an async function from a non async function");
-
-    // Check that if the apply is of a noreturn callee, make sure that an
-    // unreachable is the next instruction.
-    if (AI->getModule().getStage() == SILStage::Raw ||
-        !AI->isCalleeNoReturn())
-      return;
-    require(isa<UnreachableInst>(std::next(SILBasicBlock::iterator(AI))),
-            "No return apply without an unreachable as a next instruction.");
   }
 
   void checkTryApplyInst(TryApplyInst *AI) {