meson: rearrange library dependency order to avoid crash with fontconfig

In win32 build, if libass and libfontconfig appear after libmingwex
during linking, crash happens whenever fontconfig calls to opendir().

Moving them before ffmpeg makes sure they always appear first.

More info on https://github.com/shinchiro/mpv-winbuild-cmake/issues/217.

meson.build

@@ -30,8 +30,10 @@ ffmpeg = {
 libass = dependency('libass', version: '>= 0.12.2')
 pthreads = dependency('threads')
 
-dependencies = [ffmpeg['deps'],
-                libass,
+# the dependency order of libass -> ffmpeg is necessary due to
+# static linking symbol resolution between fontconfig and MinGW
+dependencies = [libass,
+                ffmpeg['deps'],
                 pthreads]
 
 features = [ffmpeg['name'], libass.name(), pthreads.name()]