Bug 864774 - Part 1: Support CPP_SOURCES in moz.build; r=gps

From a9d4b403b4f61afcfb27881c5330f95415481a40 Mon Sep 17 00:00:00 2001
Bug 864774 - Part 2: Move CPPSRCS to moz.build as CPP_SOURCES; r=joey

From 140b9201e3b5d2d8efe7af286d279c2411dbc197 Mon Sep 17 00:00:00 2001