(svn r16502) -Fix [FS#2935]: when an AI was suspended while in a function called (indirectly) via call/acall/pcall OpenTTD crashed. Fix this by disallowing AIs to be suspended while called via call/acall/pcall.

IMPORTANT FOR AI WRITERS: AIs can no longer call any DoCommand functions (change anything, build vehicles, etc.) in a function called (indirectly) via call/acall/pcall. Where possible, please rewrite your code so it doesn't use call/acall/pcall

src/script/squirrel.cpp

@@ -508,3 +508,8 @@ void Squirrel::ResetCrashed()
 {
 	this->crashed = false;
 }
+
+bool Squirrel::CanSuspend()
+{
+	return sq_can_suspend(this->vm);
+}