Fix Fastmem in JitIL for massive speed gains.

JitIL's fastmem was stubbed out when @Sonicadvance1 merged JitARMIL
into the tree. Since JitARMIL has been deleted, I simply re-arrange
the inheritance to base JitIL on Jitx86Base, so it can inherit the
backpatch function.

Povray Benchmark: 1985 seconds to 1316 seconds.