mach fat binaries mess up rdr map symbol disassembly

When a mach map is built:

`rdr -m -f _printf -D`

will incorrectly disassemble the wrong area, as rdr sucks out the 64-bit binary and all offsets are not relative to the original fat binary. To fix this, simply have all mach binary analysis use a base?

Reproduce the issue with `rdr -m -f _printf -D` on a Mach-O fat binary, then trace the Mach binary analysis that extracts the 64-bit binary and applies offsets. Done means symbol disassembly uses offsets relative to the original fat binary rather than the extracted slice.

Written by the indexing model from the issue text.