Also remap GID under non-MacOS

The manpage says that -o idmap=user maps the UID and GID, but it
apparently only mapped the UID.  The code was in place to map the GID as
well, but it was hidden behind #ifdef __APPLE__.  This commit removes
those #ifdefs, and in a couple of cases the code inside an #else, to
make the option behave as documented.

ChangeLog.rst

@@ -1,3 +1,8 @@
+Unreleased Changes
+------------------
+
+* Fixed "-o idmap=user" to map both UID and GID on all OSs.
+
 Release 3.5.1 (2018-12-22)
 --------------------------
 

sshfs.c

@@ -264,10 +264,8 @@ struct sshfs {
  int server_version;
  unsigned remote_uid;
  unsigned local_uid;
-#ifdef __APPLE__
  unsigned remote_gid;
  unsigned local_gid;
-#endif
  int remote_uid_detected;
  unsigned blksize;
  char *progname;
@@ -789,17 +787,12 @@ static int buf_get_attrs(struct buffer *buf, struct stat *stbuf, int *flagsp)
  }
  }
 
-#ifdef __APPLE__
  if (sshfs.remote_uid_detected) {
  if (uid == sshfs.remote_uid)
  uid = sshfs.local_uid;
  if (gid == sshfs.remote_gid)
  gid = sshfs.local_gid;
  }
-#else /* !__APPLE__ */
- if (sshfs.remote_uid_detected && uid == sshfs.remote_uid)
- uid = sshfs.local_uid;
-#endif /* __APPLE__ */
  if (sshfs.idmap == IDMAP_FILE && sshfs.uid_map)
  if (translate_id(&uid, sshfs.uid_map) == -1)
  return -EPERM;
@@ -1600,10 +1593,8 @@ static void sftp_detect_uid()
 
  sshfs.remote_uid = stbuf.st_uid;
  sshfs.local_uid = getuid();
-#ifdef __APPLE__
  sshfs.remote_gid = stbuf.st_gid;
  sshfs.local_gid = getgid();
-#endif
  sshfs.remote_uid_detected = 1;
  DEBUG("remote_uid = %i\n", sshfs.remote_uid);
 
@@ -2424,17 +2415,12 @@ static int sshfs_chown(const char *path, uid_t uid, gid_t gid,
  return -EIO;
  }
 
-#ifdef __APPLE__
  if (sshfs.remote_uid_detected) {
  if (uid == sshfs.local_uid)
  uid = sshfs.remote_uid;
  if (gid == sshfs.local_gid)
  gid = sshfs.remote_gid;
  }
-#else /* !__APPLE__ */
- if (sshfs.remote_uid_detected && uid == sshfs.local_uid)
- uid = sshfs.remote_uid;
-#endif /* __APPLE__ */
  if (sshfs.idmap == IDMAP_FILE && sshfs.r_uid_map)
  if(translate_id(&uid, sshfs.r_uid_map) == -1)
  return -EPERM;