first Android release

Finally, MPD runs on Android.  For some small value of "runs".  Very
much work left, too much to describe.

configure.ac

@@ -152,6 +152,27 @@ if test -z "$prefix" || test "x$prefix" = xNONE; then
 	done
 fi
 
+dnl ---------------------------------------------------------------------------
+dnl Android
+dnl ---------------------------------------------------------------------------
+
+AC_ARG_WITH([android-sdk],
+	AS_HELP_STRING([--with-android-sdk=DIR],
+		[Directory for Android SDK]),
+		[], [with_android_sdk=no])
+
+if test x$host_is_android = xyes; then
+	if test x$with_android_sdk = xno; then
+		AC_MSG_ERROR([Android build requires option --with-android-sdk=DIR])
+	fi
+
+	if ! test -x $with_android_sdk/tools/android; then
+		AC_MSG_ERROR([Android SDK not found in $with_android_sdk])
+	fi
+fi
+
+AC_SUBST(ANDROID_SDK, [$with_android_sdk])
+
 dnl ---------------------------------------------------------------------------
 dnl Language Checks
 dnl ---------------------------------------------------------------------------