[Dependencies] Fix -emit-fine-grained-dependency-sourcefile-dot-files flag definition

Author: owenv

include/swift/Option/Options.td

@@ -193,7 +193,7 @@ HelpText<"Include within-file dependencies.">;
 
 def emit_fine_grained_dependency_sourcefile_dot_files :
 Flag<["-"], "emit-fine-grained-dependency-sourcefile-dot-files">,
-InternalDebugOpt,
+Flags<[FrontendOption, HelpHidden]>,
 HelpText<"Emit dot files for every source file.">;
 
 def driver_mode : Joined<["--"], "driver-mode=">, Flags<[HelpHidden]>,