[libclc] Fix build with Unix Makefiles (#89147)

Commit #87622 broke the build. Ninja was happy with creating the output
directories as necessary, but Unix Makefiles isn't. Ensure they are
always created.

Fixes #88626.

libclc/cmake/modules/AddLibclc.cmake

@@ -39,6 +39,10 @@ function(compile_to_bc)
     set( TARGET_ARG "-target" ${ARG_TRIPLE} )
   endif()
 
+  # Ensure the directory we are told to output to exists
+  get_filename_component( ARG_OUTPUT_DIR ${ARG_OUTPUT} DIRECTORY )
+  file( MAKE_DIRECTORY ${ARG_OUTPUT_DIR} )
+
   add_custom_command(
     OUTPUT ${ARG_OUTPUT}${TMP_SUFFIX}
     COMMAND libclc::clang