[llvm] [NFC][RA] Refactor RABasic into a Separate Header (PR #149555)

[Matthias Braun via llvm-commits]

================
@@ -0,0 +1,107 @@
+//===-- RegAllocBasic.h - Basic Register Allocator Header -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the RABasic class, which provides a minimal
+// implementation of the basic register allocator.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_REGALLOCBAISC_H_
+#define LLVM_CODEGEN_REGALLOCBAISC_H_
----------------
MatzeB wrote:

most files tend to use `LLVM_LIB_CODEGEN_XXXX_H` it seems...

https://github.com/llvm/llvm-project/pull/149555