Back out "Fix CQS signal facebook-unused-include-check in fbcode/glean/rts/tests"

Summary: /* This file only exists to make sure that ffi.h can be included in a C file. */

Reviewed By: malanka

Differential Revision: D77660208

fbshipit-source-id: 36eaa95c2a65ed86628923cb08625b468facf512

Author: Pepe Iborra

glean/rts/tests/ffi_works_as_c.c

@@ -8,6 +8,8 @@
 
 /* This file only exists to make sure that ffi.h can be included in a C file. */
 
+#include "glean/rts/ffi.h" // IWYU pragma: keep
+
 int main() {
   return 0;
 }