Fix sign problem, implement low-mem mmap wraparound

A signed value comparison meant that on 64b systems comparisons
were false when pointers > 2GB were in use (as happens in long-running
tests). Fix this to be uint.

Implement a simple wrap-around in the MAP_32BIT emulation code.

Change-Id: I09870b4755f2dca676e42e701fbb6f6eb4bb95d0
2 files changed