Use _nacl suffix for NaCl targets in src/media and the gyp file.

BUG=345453
R=bradnelson@chromium.org, dmichael@chromium.org, scherkus@chromium.org

Review URL: https://codereview.chromium.org/172253007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252612 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252612