[Android] Added tools (unix bash scripts) to recompile Android extlibs

For some reason, one might want to recompile the extlibs but this is a tedious task. That's why these scripts are provided.
Please read readme.txt before using them!

tools/android/make_all.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# Abort if no known installation of NDK
+if [ "$NDK" == "" ]
+then
+	echo "Where is the NDK location ?"
+	echo -n "NDK: "; read NDK
+	export NDK=$NDK
+fi
+
+export ANDROID_NDK=$NDK
+
+# Abort if we don't know the Android CMake toolchain location
+if [ "$ANDROID_CMAKE_TOOLCHAIN" == "" ]
+then
+	echo "Where is the Android CMake toolchain ?"
+	echo -n "ANDROID_CMAKE_TOOLCHAIN: "; read ANDROID_CMAKE_TOOLCHAIN
+	export ANDROID_CMAKE_TOOLCHAIN=$ANDROID_CMAKE_TOOLCHAIN
+fi
+
+./clean_all.sh
+
+./create_toolchains.sh
+
+./download_sources.sh
+./compile_arm.sh
+
+rm -r $PWD/build
+./download_sources.sh
+./compile_x86.sh
+
+rm -r $PWD/build
+./download_sources.sh
+./compile_mips.sh
+
+rm -r $PWD/build
+./download_sources.sh
+./compile_arm-v7a.sh