build-sys: do not install gdkwin32keys.h

Fixes: commit 89ad7893ad ("gdk: Make GdkKeymap a private api")

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

gdk/win32/meson.build

@@ -31,6 +31,7 @@ gdk_win32_sources = files([
   'gdkwin32cursor.h',
   'gdkwin32display.h',
   'gdkwin32id.c',
+  'gdkwin32keys.h',
   'gdksurface-win32.c',
 ])
 
@@ -40,7 +41,6 @@ gdk_win32_public_headers = files([
   'gdkwin32displaymanager.h',
   'gdkwin32dnd.h',
   'gdkwin32glcontext.h',
-  'gdkwin32keys.h',
   'gdkwin32misc.h',
   'gdkwin32monitor.h',
   'gdkwin32screen.h',