unix,fs: code cleanup of uv_fs_event_start for AIX
unix,fs: code cleanup of uv_fs_event_start for AIX

Remove unused variables and code. Also remove some code duplication. End
result is code is cleaner, readable and easier to step through when
debugging.

PR-URL: https://github.com/libuv/libuv/pull/825
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso