[gtk] (19 commits) ...Merge branch 'lrn/gtk4warnings' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  10b2f65... Fix wrong format strings in various places (*)
  58fc122... Remove unused variables (mostly in W32 code) (*)
  aaa4e23... Fix gdk_win32_cairo_context_end_frame prototype (*)
  bc47fa2... Fix various type mismatch warnings (*)
  0e1710a... Remove some more unused variables (*)
  8bd6936... Fix signedness issues, remove unused code (*)
  f0103ee... Remove unused functions in W32 backend (*)
  1e2ab40... Fix a missing default case warning (*)
  cacdef8... A quick and dirty fix for a circular allocation issue (*)
  3acd26c... Fix more signedness issues in W32 backend (*)
  93f8f3c... Remove unused code in gdksurface-win32.c (*)
  e73dc5c... Fix a warning about uninitialized variable (*)
  cddc9ff... Fix a typo in W32 event-handling code (*)
  411c535... Fix some warnings in W32 part of gtkmain (*)
  43d6fe2... Fix missing default switch cases in gtkimcontextsimple (*)
  9330be8... Fix missing default switch case in DllMain (*)
  0365dad... See if _MSC_VER is defined before checking its value (*)
  43f3789... Use correct stat struct for ftw() (*)
  4f63229... Merge branch 'lrn/gtk4warnings' into 'master'

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