make goto based exceptions available for 'nim cpp' (#13244)

* make goto based exceptions available for 'nim cpp'
* optimize seq.add to be comparable to C++'s emplace_back

compiler/ccgtypes.nim

@@ -608,7 +608,7 @@ proc getRecordDesc(m: BModule, typ: PType, name: Rope,
     elif m.compileToCpp:
       appcg(m, result, " : public $1 {$n",
                       [getTypeDescAux(m, typ[0].skipTypes(skipPtrs), check)])
-      if typ.isException:
+      if typ.isException and m.config.exc == excCpp:
         appcg(m, result, "virtual void raise() { throw *this; }$n", []) # required for polymorphic exceptions
         if typ.sym.magic == mException:
           # Add cleanup destructor to Exception base class