Don't install gcc-5 on Linux / gmp on Mac
Don't install gcc-5 on Linux / gmp on Mac

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