sim-se: Fix for build error in MacOS.

On MacOS the build fails because the types of readfds, writefds, and
errorfds cannot be automatically converted to fd_set*. Added casts
similar to the ones used for the FD_ZERO calls to help the compiler.

Change-Id: I40a2268f7f2ca1bece1ecafda52dfddf2212364d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47759
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed