src/fieldsplit: perf enhancements.
src/fieldsplit: perf enhancements.

- cache the output filehandles if they are likely to be written
  to. This is captured during the writes, 10% of files that get a high
  degree of writes are left open.

- compile the xform regexs.

- use the get_line_field perf tuned function for getting line values.


git-svn-id: 036a1c5f902f528d79fbac72fb947c91fe594755@387 9f305d85-0c50-0410-b3e0-65f4174694de

johan/crush-tools,johan/crush-tools,johan/crush-tools