Remove libmfx support

Intel discontinued support for it. There will be no security fixes and
updates for it anymore.

Unfortunately this means that older versions of ffmpeg will be losing
support for QSV hardware acceleration, but it's either that or knowingly
leaving people open to security issues.

scripts.d/50-mfx.sh

@@ -1,47 +0,0 @@
-#!/bin/bash
-
-SCRIPT_REPO="https://github.com/lu-zero/mfx_dispatch.git"
-SCRIPT_COMMIT="5a3f178be7f406cec920b9f52f46c1ae29f29bb2"
-
-ffbuild_enabled() {
-    [[ $TARGET == *arm64 ]] && return -1
-    [[ $ADDINS_STR != *4.4* && $ADDINS_STR != *5.0* && $ADDINS_STR != *5.1* ]] && return -1
-    return 0
-}
-
-ffbuild_dockerbuild() {
-    git-mini-clone "$SCRIPT_REPO" "$SCRIPT_COMMIT" mfx
-    cd mfx
-
-    autoreconf -i
-
-    local myconf=(
-        --prefix="$FFBUILD_PREFIX"
-        --disable-shared
-        --enable-static
-        --with-pic
-    )
-
-    if [[ $TARGET == win* || $TARGET == linux* ]]; then
-        myconf+=(
-            --host="$FFBUILD_TOOLCHAIN"
-        )
-    else
-        echo "Unknown target"
-        return -1
-    fi
-
-    ./configure "${myconf[@]}"
-    make -j$(nproc)
-    make install
-
-    ln -s libmfx.pc "$FFBUILD_PREFIX"/lib/pkgconfig/mfx.pc
-}
-
-ffbuild_configure() {
-    echo --enable-libmfx
-}
-
-ffbuild_unconfigure() {
-    echo --disable-libmfx
-}