Add aribb24 for ARIB caption support

Closes #152

scripts.d/50-aribb24/25-libpng.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+
+LIBPNG_REPO="https://github.com/glennrp/libpng.git"
+LIBPNG_COMMIT="a37d4836519517bdce6cb9d956092321eca3e73b"
+
+ffbuild_enabled() {
+    return 0
+}
+
+ffbuild_dockerbuild() {
+    git-mini-clone "$LIBPNG_REPO" "$LIBPNG_COMMIT" libpng
+    cd libpng
+
+    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
+
+    export CPPFLAGS="$CPPFLAGS -I$FFBUILD_PREFIX/include"
+
+    ./configure "${myconf[@]}"
+    make -j$(nproc)
+    make install
+}

scripts.d/50-aribb24/50-libaribb24.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+
+ARIBB24_REPO="https://github.com/nkoriyama/aribb24.git"
+ARIBB24_COMMIT="5e9be272f96e00f15a2f3c5f8ba7e124862aec38"
+
+ffbuild_enabled() {
+    return 0
+}
+
+ffbuild_dockerstage() {
+    to_df "RUN --mount=src=${SELF},dst=/stage.sh --mount=src=patches/aribb24,dst=/patches run_stage /stage.sh"
+}
+
+ffbuild_dockerbuild() {
+    git-mini-clone "$ARIBB24_REPO" "$ARIBB24_COMMIT" aribb24
+    cd aribb24
+
+    for patch in /patches/*.patch; do
+        echo "Applying $patch"
+        git am < "$patch"
+    done
+
+    # Library switched to LGPL on master, but didn't bump version since.
+    # FFmpeg checks for >1.0.3 to allow LGPL builds.
+    sed -i 's/1.0.3/1.0.4/' configure.ac
+
+    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
+}
+
+ffbuild_configure() {
+    echo --enable-libaribb24
+}
+
+ffbuild_unconfigure() {
+    echo --disable-libaribb24
+}