linux: improve warnings when NSS/PR shutdowns fail
linux: improve warnings when NSS/PR shutdowns fail

Make one into a LOG(INFO) since it's relatively harmless;
add comments on the other with a link to the bug.

BUG=4609,18410

Review URL: http://codereview.chromium.org/159836

git-svn-id: http://src.chromium.org/svn/trunk/src@22394 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1d700c994789b78b4617932d52f2fc465981ed10
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser