Extended discovery scan function to be able to discover IBM TS4300 Tape Libraries.

NOTE: This change was not accepted by checkmk development team for the master development tree because it will cause
that all snmp devices are scanned for OID .1.3.6.1.4.1.14851.3.1.3.5.0 during discovery.

Usually only sysDesc .1.3.6.1.2.1.1.1.0 is scanned but TS4300 does not provide one.

Root Cause of the problem is that IBM fails to provide a proper sysDesc and you get "Cannot fetch system description OID .1.3.6.1.2.1.1.1.0"

See also:

• https://github.com/Checkmk/checkmk/pull/593
  
• https://forum.checkmk.com/t/ibm-ts-4300-got-empty-snmp-response/31004/19
  
• https://exchange.checkmk.com/u/grepmeister