meson: Fix compliation with avisynth enabled

Still crashes when loading a video.

meson.build

@@ -222,6 +222,7 @@ endforeach
 
 if host_machine.system() == 'windows' and get_option('avisynth').enabled()
     conf.set('WITH_AVISYNTH', 1) # bundled separately with installer
+    deps += cc.find_library('avifil32', required: true)
 endif
 
 if host_machine.system() == 'windows' and not get_option('directsound').disabled()

src/meson.build

@@ -174,6 +174,7 @@ elif host_machine.system() == 'windows'
         'avisynth_wrap.cpp',
         'font_file_lister_gdi.cpp',
         # 'libass_gdi_fontselect.cpp',
+        'audio_provider_avs.cpp',
         'video_provider_avs.cpp',
     )