Fix #3988 ( not do the preprocessor again in reason mode)

Author: bobzhang

jscomp/main/js_main.ml

@@ -19,7 +19,8 @@ let process_implementation_file ppf name =
 
 let setup_reason_context () = 
   Js_config.is_reason := true;
-  Lazy.force Super_main.setup;
+  Clflags.preprocessor := None ; (* FIX #3988*)
+  Lazy.force Super_main.setup;  
   Lazy.force Reason_outcome_printer_main.setup
 
 let reason_pp ~sourcefile  = 

lib/4.06.1/whole_compiler.ml

@@ -139922,7 +139922,8 @@ let process_implementation_file ppf name =
 
 let setup_reason_context () = 
   Js_config.is_reason := true;
-  Lazy.force Super_main.setup;
+  Clflags.preprocessor := None ; (* FIX #3988*)
+  Lazy.force Super_main.setup;  
   Lazy.force Reason_outcome_printer_main.setup
 
 let reason_pp ~sourcefile  =