adding ref for VS2012 compat
adding ref for VS2012 compat

FStarLang/FStar,YaccConstructor/FStar,MallabaevAzamat/FStar,aa755/FStar,A-Manning/FStar,A-Manning/FStar,MallabaevAzamat/FStar,YaccConstructor/FStar,YaccConstructor/FStar,aa755/FStar,aa755/FStar,hoheinzollern/FStar,msprotz/FStar,FStarLang/FStar,aa755/FStar,msprotz/FStar,hoheinzollern/FStar,msprotz/FStar,MallabaevAzamat/FStar,FStarLang/FStar,MallabaevAzamat/FStar,YaccConstructor/FStar,A-Manning/FStar,hoheinzollern/FStar,msprotz/FStar,hoheinzollern/FStar