When looking at /proc/self/maps, we need to take into account the offset
in addition to the start and end addresses, otherwise --prof get's
confused with binaries produced by lld.

Change-Id: If6b484a8080a0393e91174c114dafe9a11964e8d
Reviewed-on: https://chromium-review.googlesource.com/720371Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48574}