set SDLMIXER_VENDORED to ON and vendor the required libraries into libs/SDL3_mixer/external

disable SDLMIXER_VORBIS_VORBISFILE
add ogg v1.3.5-SDL
add opus v1.4.x-SDL
add opusfile v0.13-git-SDL

libs/SDL3_mixer/external/opus/tests/opus_build_test.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+tarball=`realpath "$1"`
+nb_tests="$2"
+oldvectors=`realpath "$3"`
+newvectors=`realpath "$4"`
+base=`basename "$tarball" .tar.gz`
+
+tar xvf "$tarball" > /dev/null 2>&1
+cd "$base"
+
+if [ $? -ne 0 ]
+then
+        echo cannot go to "$base"
+        exit 1
+fi
+
+mkdir build_tests
+
+configure_dir=`pwd`
+seq -w "$nb_tests" | parallel --halt now,fail=10 -j +2 -q ../random_config.sh "build_tests/run_{}" "$configure_dir" "$oldvectors" "$newvectors"
+
+if [ $? -ne 0 ]
+then
+        echo Check found errors
+        exit 1
+else
+        echo No error found
+fi