Fixing minidump_dump to handle nacl dumps.

Fixing minidump_dump to handle nacl dumps.

Since nacl was not listed in decoding the code identifier, minidump_dump
produces errors like this (and non-zero return code):
2013-09-05 13:41:04: minidump.cc:2044: ERROR: MinidumpModule code_identifier
requires known platform, found 0x8205

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3424
TEST=tested with minidumps from nacl locally
R=mark@chromium.org,mseaborn@chromium.org

[mseaborn]

It's not clear to me what you're fixing.  What's the output of minidump_dump
before and after this change?  Can you add an example to the commit message?

The change itself LGTM.

[Mark Mentovai]

LGTM. On non-Windows, there are no code identifiers, only debug identifiers.

[bradnelson]

Updated description