Prepare www/firefox a bit for ESR45:
- [e10s] Make layers.progressive-paint;true work at least on 11.0-CURRENT
- Chase bundled versions for system dependencies
- Drop unused/broken system opus and speex support
Changes: https://www.mozilla.org/firefox/45.0/releasenotes/
Changes: https://www.mozilla.org/firefox/38.7.0/releasenotes/
Security: 2225c5b4-1e5a-44fc-9920-b3201c384a15
MFH: 2016Q1 (release candidate)