z/OS: changes to DISPLAY command output

Fields with a blank or null value shown in the output of DISPLAY commands are now displayed without a space between the brackets.

This change is relevant to all blank or null value fields output from a DISPLAY command.

For example, in previous releases of IBM® MQ for z/OS®, the output of DISPLAY QMGR SSLKEYR, where the SSLKEYR field contained a blank or NULL value, was SSLKEYR( ).

From IBM MQ for z/OS Version 8.0, the output is SSLKEYR().