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

Review URL: https://breakpad.appspot.com/628002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1211 4c0a9323-5329-0410-9bdc-e9ce6186880e