Created attachment 583432 [details] [diff] [review]
vpx_codec_control_ is used by some static functions defined in vpx_codec.h. Usually, if such functions are not used, whey should be skipped by compiler. However, for some reason, it's not the case on unoptimized 64-bit mingw-w64 builds. Exporting it from gkmedias.dll will avoid similar potential problems on other builds as well.
I mean https://hg.mozilla.org/mozilla-central/rev/d78b7af89987