test: fix test/test-tty.c for AIX
test: fix test/test-tty.c for AIX

'/dev/random' causes 'isatty()' to return 1 on AIX[1]. This causes
an issue where 'dev/tty' is opened (hard coded in
src/unix/tty.c:uv_tty_init). Tried to replace the hardcoded value with
what is returned by 'ttyname()' but on AIX all that is returned is
'/dev/'.

This seems to be a bug with the AIX kernel.

[1]http://goo.gl/wGa7mf

PR-URL: https://github.com/libuv/libuv/pull/624
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: Saúl Ibarra Corretgé <8a7991f6950ea189abf159d6ec98d2fcc13dc5f6@gmail.com>

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