Disable fast memory access optimizations

LLVM's fast memory access optimization will use floating point VMOV
instructions as fast memcpy intrinsics.

At least in QEMU, these instructions were corrupting data and just
generally doing a poor job at functioning correcly (maybe the FPU needs
to be turned on before using them??).

Disabling them causing LLVM to emit normal MOV instructions, and now the
iterator in write() actually works!
Remove cruft

Remove extra testing or fixup code that is no longer necessary.