[network-manager-applet] (8 commits) ...build: merge branch 'th/clang-build-fixes'

[Thomas Haller <thaller src gnome org>]

Summary of changes:

  0d10780... build: refactor compiler_warnings.m4 macro (*)
  c090c3a... build: fix detecting support for -Wno-* compiler flags (*)
  440e8f5... build: disable warnings that trigger known clang problems (*)
  63dce57... build: fix clang + glib 2.43 build (*)
  a090f5d... build/trivial: reorder tested compiler warnings (*)
  77ad94d... build: fix inclusion guard for src/applet-vpn-request.h (*)
  34b6bc4... applet: fix compiler warning about enum type mismatch (*)
  c531937... build: merge branch 'th/clang-build-fixes' (*)

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