[clangd] Fix builds after 4ddae8b

(cherry picked from commit 9ffef0f)

Author: kadircet

clang-tools-extra/clangd/test/CMakeLists.txt

@@ -28,14 +28,11 @@ configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 
-# Copy an empty compile_commands.json to override the compile_commands.json
-# in the top level build directory.  Or if a clangd test involves creating a
-# temporary source file in the build directory and run clangd to check it,
-# it can pick up unrecognizable command options when LLVM is built with
-# another compiler or a different version of Clang.
-configure_file(
-  ${CMAKE_CURRENT_SOURCE_DIR}/compile_commands.json
-  ${CMAKE_CURRENT_BINARY_DIR}/compile_commands.json
+# Copy an empty compile_flags.txt to make sure tests don't pick up arbitrary
+# commands from parents.
+file(
+  TOUCH
+  ${CMAKE_CURRENT_BINARY_DIR}/compile_flags.txt
 )
 
 add_lit_testsuite(check-clangd "Running the Clangd regression tests"