[gjs] (13 commits) ...Merge branch 'master.windows' into 'master'

[Philip Chimento <pchimento src gnome org>]

Summary of changes:

  0e5478c... gi/*.h: Be clear about the templates used with friend class (*)
  5d222f4... Fix building of gjs_profiler_chain_signal() on Windows (*)
  c61de41... gjs/debugger.cpp: Fix build on Windows (*)
  9796da0... gjs/context.cpp: Build heap dumping only on UNIX (*)
  dba6f0b... gjs: Avoid ambiguity in smart pointers (*)
  a76011f... gjs-util.c: Fix building gjs_open_bytes() on Windows (*)
  c455da1... gjs: Work around Visual Studio 2017 bug (*)
  6c00884... gi: Initialize pointer members of wrapper classes (*)
  b1b9f3b... CI: Remove "Total errors found" line from cpplint output (*)
  e3492ff... win32/NMake: Require Visual Studio 2017 15.6 or later (*)
  5a5d8eb... Visual Studio builds: Refine things a bit (*)
  169e21f... win32/README.txt: Update SpiderMonkey build instructions (*)
  173741d... Merge branch 'master.windows' into 'master'

(*) This commit already existed in another branch; no separate mail sent