Add missing LOCK(cs_main)
gitian: Add OSX build descriptors

Github-Pull: #4185
Rebased-By: Wladimir J. van der Laan
Rebased-From: bb5da27, 2288206, 7fe8fe6, f76db78, ebcf375, fa1ed7c, 397e9b8
qt: Periodic language update
Merge pull request #4204

305ccaa Add missing LOCK(cs_main) (Pieter Wuille)