Set spliced LOAD segment's memsz equal to filesz.

Set spliced LOAD segment's memsz equal to filesz.

Current packing sets the spliced LOAD segment's memsz to larger than
its filesz.  This causes the runtime linker to create a 'zero' mapping
to pad from filesz to memsz.

This isn't a problem -- the mapping sits on already reserved address
space and uses no real memory -- but 'null' mappings like this appear
in /proc/pid/maps and can disrupt or confuse tools which read and
parse it, for example Breakpad.

This change makes the spliced LOAD segment's memsz and filesz equal.
It also tidies code a little so that it is now more obvious when
filesz is equal to memsz, and vaddr is equal to paddr.

Also, rebuild test data to match.

BUG=385553
Committed: https://crrev.com/b344e78c65330d3b2d4f767e91349f2a6004e960
Cr-Commit-Position: refs/heads/master@{#295459}

[simonb (inactive), 2014-09-17 11:35:30]

simonb@chromium.org changed reviewers:
+ anton@chromium.org

[Anton, 2014-09-18 11:31:35]

The CQ bit was checked by anton@chromium.org

[Anton, 2014-09-18 11:31:35]

lgtm

[commit-bot: I haz the power, 2014-09-18 11:31:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/571333003/1

[commit-bot: I haz the power, 2014-09-18 12:31:24]

Committed patchset #1 (id:1) as d33f355aa3ca15084fe40f01f231e3a62733e88a

[commit-bot: I haz the power, 2014-09-18 12:31:52]

Patchset 1 (id:??) landed as
https://crrev.com/b344e78c65330d3b2d4f767e91349f2a6004e960
Cr-Commit-Position: refs/heads/master@{#295459}