os_get_passwd: Fix potential omission of gid/uid values in non-Window…

…s environments

-1 only has special meaning on Windows, and gid and uid are always set to -1 on Windows, so we can just omit the gid and uid fields on Windows instead of checking for -1. This is a better fix for luvit#589, and a follow up to luvit#590.

src/misc.c

@@ -373,14 +373,15 @@ static int luv_os_get_passwd(lua_State* L) {
  lua_pushstring(L, pwd.username);
  lua_setfield(L, -2, "username");
  }
- if (pwd.uid != -1) {
- lua_pushinteger(L, pwd.uid);
- lua_setfield(L, -2, "uid");
- }
- if (pwd.gid != -1) {
- lua_pushinteger(L, pwd.gid);
- lua_setfield(L, -2, "gid");
- }
+ // From the uv_os_get_passwd docs:
+ // "On Windows, uid and gid are set to -1 and have no meaning"
+ // so we omit these fields on Windows.
+#ifndef _WIN32
+ lua_pushinteger(L, pwd.uid);
+ lua_setfield(L, -2, "uid");
+ lua_pushinteger(L, pwd.gid);
+ lua_setfield(L, -2, "gid");
+#endif
  if (pwd.shell) {
  lua_pushstring(L, pwd.shell);
  lua_setfield(L, -2, "shell");