Fix String.ends_with() for empty string arguments

(cherry picked from commit 1d0437c95b7d91ad91b9cd14026b7c7996ef9358)

core/ustring.cpp

@@ -2709,10 +2709,15 @@ int String::rfindn(const String &p_str, int p_from) const {
 
 bool String::ends_with(const String &p_string) const {
 
+	int l = p_string.length();
+	if (l == 0) {
+		return true;
+	}
+
 	int pos = find_last(p_string);
 	if (pos == -1)
 		return false;
-	return pos + p_string.length() == length();
+	return pos + l == length();
 }
 
 bool String::begins_with(const String &p_string) const {