Pacify MSVC warnings for numeric.c, proc.c, and symbol.c

src/numeric.c

@@ -699,7 +699,7 @@ mrb_fixnum_mul(mrb_state *mrb, mrb_value x, mrb_value y)
     if ((a != 0 && c/a != b) || !FIXABLE(c)) {
       return mrb_float_value(mrb, (mrb_float)a*(mrb_float)b);
     }
-    return mrb_fixnum_value(c);
+    return mrb_fixnum_value((mrb_int)c);
   }
   return mrb_float_value(mrb, (mrb_float)a * mrb_to_flo(mrb, y));
 }

src/proc.c

@@ -126,7 +126,7 @@ mrb_proc_cfunc_env_get(mrb_state *mrb, mrb_int idx)
   if (!e) {
     mrb_raise(mrb, E_TYPE_ERROR, "Can't get cfunc env from cfunc Proc without REnv.");
   }
-  if (idx < 0 || MRB_ENV_STACK_LEN(e) <= idx) {
+  if (idx < 0 || (mrb_int)MRB_ENV_STACK_LEN(e) <= idx) {
     mrb_raisef(mrb, E_INDEX_ERROR, "Env index out of range: %S (expected: 0 <= index < %S)",
                mrb_fixnum_value(idx), mrb_fixnum_value(MRB_ENV_STACK_LEN(e)));
   }

src/symbol.c

@@ -68,7 +68,7 @@ sym_intern(mrb_state *mrb, const char *name, size_t len, mrb_bool lit)
   sym = ++mrb->symidx;
   if (mrb->symcapa < sym) {
     if (mrb->symcapa == 0) mrb->symcapa = 100;
-    else mrb->symcapa *= 1.2;
+    else mrb->symcapa = (size_t)(mrb->symcapa * 1.2);
     mrb->symtbl = (symbol_name*)mrb_realloc(mrb, mrb->symtbl, sizeof(symbol_name)*(mrb->symcapa+1));
   }
   sname = &mrb->symtbl[sym];