[glibmm] (18 commits) ...Merge branch 'kjellahl/meson-build-master' into 'master'

[Kjell Ahlstedt <kjellahl src gnome org>]

Summary of changes:

  d378578... Add support for building glibmm with Meson (*)
  478ab58... meson.build: Always look for libsigc++ via pkg-config (*)
  5691f7d... meson.build: Allow Visual Studio builds in GIT checkouts (*)
  2b6cc80... tools: Use POSIX-style path for m4 in gmmproc (*)
  7fd7040... meson.build: Disable warning C4589 on Visual Studio (*)
  1e37c0e... glib/glibmm/meson.build: Use glibmm-int rule for all builds (*)
  456508a... gio/giomm/meson.build: Use giomm-int rule for all builds (*)
  d1abe57... dbusconnection.ccg: Include giomm/unixfdlist.h on *NIX only (*)
  949d3b6... examples: Don't build child_watch and iochannel_stream on W (*)
  150bee0... glibmm_interface_move test: Avoid warnings in test_IFace_ge (*)
  5f7f9b2... examples/thread/dispatcher.cc: Make C++17 compliant (*)
  07c72cb... meson: Build items in tools/extra_defs_gen on MSVC too (*)
  fa4817f... tools: Fix 'meson dist' (*)
  ec9b9bc... Makefile.am: Distribute files necessary for building with M (*)
  1a5af7b... Meson build: Add some dependencies when generating source f (*)
  8e09f45... meson.build: Tidy up a bit (*)
  63cfffc... MSVC NMake: Allow builds from Meson-generated tarballs (*)
  bcdb1a5... Merge branch 'kjellahl/meson-build-master' into 'master'

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