Bug 1038406 - Privatize destructor for ResourceSocketListener. r=cpearce

Bonus fix: remove redundant `public:`.
Bug 1036784 - Extend freeSpanAllocate to do all the things that FreeList::allocate does, and rename it to freeListAllocate. r=terrence
Bug 1035786 - Fix member variable initialisation order in LogMessage stub in Linux Sandbox.cpp. r=jld
Bug 1035786 - Avoid warning-as-error sandbox build failure with an explicit cast. r=gdestuynder

getpid() is never negative, so this is safe.
Bug 1035786 - Fix namespace bug in Linux sandbox LOG_ERROR macro. r=jld