Remove check for useSIGIO option
Commit 6a5a4e60 removed the option to configure useSIGIO option. Indeed, the xfree86 SIGIO support was reworked to use internal versions of OsBlockSIGIO and OsReleaseSIGIO.
As a result, useSIGIO is no longer needed and can dropped
Signed-off-by: Prabhu Sundararaj firstname.lastname@example.org
Signed-off-by: Mylène Josserand email@example.com
Signed-off-by: Fabrice Fontaine firstname.lastname@example.org