MFH: r408984 r410176 r410186

www/firefox: simplify upstream graphite2 update-helper

www/firefox{,-esr}: update to 45.0 (rc2) / 38.7.0

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 [1]
• 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/
PR: 207686 [1]
Security: 2225c5b4-1e5a-44fc-9920-b3201c384a15
Approved by: ports-secteam (feld, merge conflict blanket)