-smb option requires full path for Samba sharing to work

This issue has been reported on qemu-devel a looong time ago: https://lists.gnu.org/archive/html/qemu-devel/2005-12/msg00141.html

QEMU version 2.2.1-4 on Arch Linux x86_64

Steps to reproduce:

host$ mkdir share
host$ chmod o+rwx share
host$ qemu <other options> -smb share

vm$ smbclient //10.0.2.4/qemu -N
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
Domain=[WORKGROUP] OS=[Windows 6.1] Server=[Samba 4.2.1]
tree connect failed: NT_STATUS_BAD_NETWORK_NAME
vm$ poweroff

Workaround:

host$ qemu <other options> -smb /full/path/to/share

vm$ $ smbclient //10.0.2.4/qemu -N
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
Domain=[WORKGROUP] OS=[Windows 6.1] Server=[Samba 4.2.1]
smb: \> ls
  .                                   D        0  Sat May  2 19:57:31 2015
  ..                                  D        0  Sat May  2 19:57:31 2015

		961302540 blocks of size 1024. 637557248 blocks available
smb: \> quit

Please, please fix this gotcha, whether in the documentation or in code. it can cause some serious bouts of hair-pulling.

-Alain