compiler: remove parentHandle from calling convention

This removes the parentHandle argument from the internal calling convention.
It was formerly used to implment coroutines.
Now that coroutines have been removed, it is no longer necessary.

compiler/compiler.go

@@ -967,9 +967,7 @@ func (b *builder) createFunction() {
 	// method).
 	var context llvm.Value
 	if !b.info.exported {
-		parentHandle := b.llvmFn.LastParam()
-		parentHandle.SetName("parentHandle")
-		context = llvm.PrevParam(parentHandle)
+		context = b.llvmFn.LastParam()
 		context.SetName("context")
 	}
 	if len(b.fn.FreeVars) != 0 {
@@ -1505,9 +1503,6 @@ func (b *builder) createFunctionCall(instr *ssa.CallCommon) (llvm.Value, error)
 		// This function takes a context parameter.
 		// Add it to the end of the parameter list.
 		params = append(params, context)
-
-		// Parent coroutine handle.
-		params = append(params, llvm.Undef(b.i8ptrType))
 	}
 
 	return b.createCall(callee, params, ""), nil