xtool: utilize llvm-config to find LLVM executables

xtool/env/llvm/llvm_config_linux_llvm17.go

@@ -0,0 +1,21 @@
+//go:build !byollvm && linux && !llvm14 && !llvm15 && !llvm16
+
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package llvm
+
+const ldLLVMConfigBin = "/usr/lib/llvm-17/bin/llvm-config"