Add MinidumpRVAListWriter and test

Add MinidumpRVAListWriter and test.

This will be used as the foundation for writing a list of
MinidumpUTF8String objects. MinidumpUTF8String (and UTF-16
MINIDUMP_STRING) objects are never referenced by
MINIDUMP_LOCATION_DESCRIPTOR because they carry their own lengths.
Instead, they are always referenced by RVA.

The list of MinidumpUTF8String objects will be used for the module
annotations vector.

TEST=minidump_test MinidumpRVAListWriter.*
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/a980409288f7831ec948d08e66729100fdf4d398

[Mark Mentovai, 2014-11-06 17:38:28]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Mark Mentovai, 2014-11-06 17:39:09]

This builds on (and updates) https://codereview.chromium.org/707543002/, and
makes use of (but does not strictly require)
https://codereview.chromium.org/708803002/.

[Mark Mentovai, 2014-11-06 21:54:56]

Updated to rebase and integrate review feedback from
https://codereview.chromium.org/704333002.

[Robert Sesek, 2014-11-07 14:42:32]

LGTM

[Mark Mentovai, 2014-11-07 14:44:14]

Committed patchset #4 (id:60001) manually as
a980409288f7831ec948d08e66729100fdf4d398 (presubmit successful).