changed get_obase and cdo_get_command_string to return std::string, adapted code accordingly

4 jobs for develop in 15 minutes and 54 seconds (queued for 5 seconds)
Status Name Job ID Coverage
  Build
passed build-gcc64 #34184
xen mistral

00:03:25

passed build-intel18 #34185
xen mistral

00:09:54

 
  Check
passed check-gcc64 #34186
xen mistral

00:05:29

passed check-intel18 #34187
xen mistral

00:05:59