Fix fastmem in JitIL after 755bd2c4.

That commit reorganized fastmem a bit; I wrote it before the patch to
support fastmem in JitIL landed, and forgot to edit it to account for
the fact.  Since JitILBase now derives from Jitx86Base, the HandleFault
override can just be removed.
Merge pull request #1158 from comex/its-like-i-have-it-out-for-jitil-or-something

Fix fastmem in JitIL after 755bd2c4.