Fix virtual folder names

[lmagyar]

fixes #343

related #207 is fixed with #345

Note: This is my first ever Android code, tested on the emulator and on real phone (Samsung A8, Android 9.0).

sshfs-win before (can't access the folders):

 Volume in drive X has no label.
 Volume Serial Number is 2C8E-EB18

 Directory of X:\

1970.01.01  02:00    <DIR>          \fs
1970.01.01  02:00    <DIR>          \rosaf
1970.01.01  02:00    <DIR>          \saf
1970.01.01  02:00    <DIR>          \superuser
               0 File(s)              0 bytes
               4 Dir(s)  1 073 741 824 000 bytes free

After

 Volume in drive X has no label.
 Volume Serial Number is 6940-EBE8

 Directory of X:\

1970.01.01  02:00    <DIR>          fs
1970.01.01  02:00    <DIR>          rosaf
1970.01.01  02:00    <DIR>          saf
1970.01.01  02:00    <DIR>          superuser
               0 File(s)              0 bytes
               4 Dir(s)  1 073 741 824 000 bytes free

SFTP Drive before (can access the folders with these strange names):

 Volume in drive X is lmagyar
 Volume Serial Number is 1234-5678

 Directory of X:\

1970.01.01  02:00    <DIR>          $fs$fs
1970.01.01  02:00    <DIR>          $fs$superuser
1970.01.01  02:00    <DIR>          $fs$saf
1970.01.01  02:00    <DIR>          $fs$rosaf
               0 File(s)              0 bytes
               4 Dir(s)  9 223 372 036 854 775 296 bytes free

After

 Volume in drive X is android-emulator
 Volume Serial Number is 1234-5678

 Directory of X:\

1970.01.01  02:00    <DIR>          fs
1970.01.01  02:00    <DIR>          superuser
1970.01.01  02:00    <DIR>          saf
1970.01.01  02:00    <DIR>          rosaf
               0 File(s)              0 bytes
               4 Dir(s)  9 223 372 036 854 775 296 bytes free

[wolpi]

looks good, thanks