Add it back

Author: tannewt

ports/zephyr-cp/cptools/cpbuild.py

@@ -353,6 +353,7 @@ async def preprocess(
                 depfile,
                 "-c",
                 source_file,
+                self.cflags_file,
                 *flags,
                 "-o",
                 output_file,
@@ -384,6 +385,7 @@ async def compile(
         await run_command(
             [
                 self.c_compiler,
+                self.cflags_file,
                 "-MMD",
                 "-c",
                 source_file,