[Dillo-dev] [patch] remove old comment from src/IO/IO.c

There is an outdated comment in src/IO/IO.c. hg blame src/IO/IO.c also shows that it is older than the code. This patch removes comment. #defines are similar to SHUT_RD, SHUT_WR and SHUT_RDWR, but shutdown is not used: code just dCloses descriptor when both sides are asked to be closed.