[gtksourceview] (8 commits) ...build: Add instructions on building with Meson using Visual Studio

[Christian Hergert <chergert src gnome org>]

Summary of changes:

  5b7386d... meson.build: Manually search for libxml2 on MSVC if needed (*)
  26da2dc... meson.build: Don't check for GCC CFlags on MSVC (*)
  5235250... MSVC builds: Move our math.h to win32/ (*)
  39ef0bf... meson: Fix Visual Studio DLL builds (*)
  e8dfda6... gtksourceutils.c: Don't define variables in a for loop stat (*)
  411a2d4... test-int2str.c: Use g_snprintf() (*)
  dff943e... build: Drop the Visual Studio projects (*)
  511a74d... build: Add instructions on building with Meson using Visual (*)

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