www/firefox: update to 47.0 (rc2) / 45.2esr

• Adjust firefox-esr-i18n for linux-firefox after r414580
• Unbreak DTRACE=on + DEBUG=on [1]
• Unbreak FFMPEG=off [2]

Changes: https://www.mozilla.org/firefox/47.0/releasenotes/
Changes: https://www.mozilla.org/firefox/45.2.0/releasenotes/
Security: 8065d37b-8e7c-4707-a608-1b0a2b8509c3
PR: 200845, 209952 [1], 209308 [2]
MFH: 2016Q2