Add support for ioctl(fd, TIOCSIG, signal_number) which used
to issue a false complaint. Fixes BZ #339706
Source patch by David Herrmann (dh.herrmann@gmail.com).
Testcase by myself.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14646 a5019735-40e9-0310-863c-91ae7b9d1cf9