More pre-2.3 build tweaks for the OS/2 EMX port:

More pre-2.3 build tweaks for the OS/2 EMX port:

- more clean up of the generated import library definiton (.DEF file)
  following checking of patch 770521, and tightening of the sed regexps.

- use -O3 even with gcc 2.8.1 - worth nearly 10% with 2.3; worth
  nothing with 2.2.x.

- clean up a couple of whitespace issues introduced by a cut'n'paste.