fix 'DEBUGCPPUNIT=TRUE make subsequenttest'
fix 'DEBUGCPPUNIT=TRUE make subsequenttest'

When running a unit test under GDB, we do not want to prefix the
cppunittester executable with the LD_LIBRARY_PATH, because that has
already happened before the "gdb --args" part of the command line.

Change-Id: If3f81ba3fc3e5260142d7e9c2d4a78e9ca63382c
Reviewed-on: https://gerrit.libreoffice.org/1532
Reviewed-by: Tor Lillqvist <a9ff1a38c0d094d92725714af3aa7948469a0905@iki.fi>
Tested-by: Tor Lillqvist <a9ff1a38c0d094d92725714af3aa7948469a0905@iki.fi>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core