android: Define Make variables for Android version

Define the following Make variables:
    MESA_ANDROID_MAJOR_VERSION
    MESA_ANDROID_MINOR_VERSION
    MESA_ANDROID_VERSION

These variable will allow us to make version-dependent decisions on
library dependencies. In particular, building Mesa against JellyBean will
require libsync.

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
diff --git a/Android.mk b/Android.mk
index 6a3014c..80c0e13 100644
--- a/Android.mk
+++ b/Android.mk
@@ -30,6 +30,11 @@
 # module will also be built.  DRI modules will be loaded by libGLES_mesa.
 
 MESA_TOP := $(call my-dir)
+
+MESA_ANDROID_MAJOR_VERSION := $(word 1, $(subst ., , $(PLATFORM_VERSION)))
+MESA_ANDROID_MINOR_VERSION := $(word 2, $(subst ., , $(PLATFORM_VERSION)))
+MESA_ANDROID_VERSION := $(MESA_ANDROID_MAJOR_VERSION).$(MESA_ANDROID_MINOR_VERSION)
+
 MESA_COMMON_MK := $(MESA_TOP)/Android.common.mk
 MESA_PYTHON2 := python