Include build number in aapt version

Teams are constantly confused over which version of aapt
they are running. Include the build number from the
Android build system in the binary. Can be retrieved by executing
'aapt version'.

Change-Id: I9165c7d01f977344e143c2cb4dd963310ab28b72
diff --git a/tools/aapt/Command.cpp b/tools/aapt/Command.cpp
index 5d146d6..bdbf47b 100644
--- a/tools/aapt/Command.cpp
+++ b/tools/aapt/Command.cpp
@@ -24,6 +24,10 @@
 
 using namespace android;
 
+#ifndef AAPT_VERSION
+    #define AAPT_VERSION ""
+#endif
+
 /*
  * Show version info.  All the cool kids do it.
  */
@@ -32,7 +36,7 @@
     if (bundle->getFileSpecCount() != 0) {
         printf("(ignoring extra arguments)\n");
     }
-    printf("Android Asset Packaging Tool, v0.2\n");
+    printf("Android Asset Packaging Tool, v0.2-" AAPT_VERSION "\n");
 
     return 0;
 }