Initial commit

added libraries:
opus
flac
libsndfile

updated:
libvorbis
libogg
openal

- Everything works as expected for now. Bare in mind libsndfile needed the check for whether or not it could find the xiph libraries removed in order for this to work.

Engine/lib/libsndfile/Building-for-Android.md

@@ -0,0 +1,46 @@
+# Building for Android
+
+Assuming the Android Ndk is installed at location `/path/to/toolchain`, building
+libsndfile for Android (arm-linux-androideabi) should be as simple as:
+```
+autoreconf -vif
+export ANDROID_TOOLCHAIN_HOME=/path/to/android/toolchain
+./Scripts/android-configure.sh
+make
+```
+The `Scripts/android-configure.sh` contains four of variables; `ANDROID_NDK_VER`,
+`ANDROID_GCC_VER`, `ANDROID_API_VER` and `ANDROID_TARGET` that can be overridden
+by setting them before the script is run.
+
+Since I (erikd), do almost zero Android development, I am happy accept patches
+for this documentation and script to improve its utility for real Android
+developers.
+
+---
+
+## Using CMake
+
+(Tested on Linux)
+
+For convenience, export the following variables:
+
+```
+export ANDROID_ABI=arm64-v8a
+export ANDROID_PLATFORM_API_LEVEL=29
+export NDK_ROOT=/path/to/android/ndk
+```
+
+Set `ANDROID_ABI`,  `ANDROID_PLATFORM_API_LEVEL`  according to your target system. Now cd into the libsndfile root directory, and run
+
+```
+cmake -S . -B build  -DCMAKE_TOOLCHAIN_FILE=$NDK_ROOT/build/cmake/android.toolchain.cmake -DANDROID_ABI=$ANDROID_ABI -DANDROID_PLATFORM=$ANDROID_PLATFORM_API_LEVEL
+```
+
+cd into `build` and run make
+
+```
+cd build
+make [-j <number of parallel jobs>]
+```
+
+This will build libsndfile for android.