Deal with *.tmp.msg after mkcatdefs failure

Deal with *.tmp.msg after mkcatdefs failure

BSD make interrupts shell pipeline after
if it cannot run the command:

rm -f Mrm.msg
ln -s ../../../../imports/motif/localized/de_DE.ISO8859-1/msg/Mrm.msg Mrm.msg
Running mkcatdefs for Mrm.cat with LANG set to de_DE.ISO8859-1
(  rm -f Mrm.cat Mrm.tmp.msg;  LANG=de_DE.ISO8859-1;  export LANG;  ../../../../imports/motif/localized/util/mkcatdefs Mrm Mrm.msg -h > Mrm.tmp.msg;  gencat  Mrm.cat Mrm.tmp.msg;  rm -f Mrm.tmp.msg  )
../../../../imports/motif/localized/util/mkcatdefs: not found
*** Error code 127

After this, an empty Mrm.tmp.msg is left.