Move GetAndroidToolsDir to common location.

Move the code which looks for the prebuilts directory
to CommonRuntimeTest and add test for it.

Change-Id: Id804de31c466656957fdd4b6a470f80a00477aed
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index 5fbc2ee..9917378 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -22,6 +22,7 @@
 
 #include <string>
 
+#include "arch/instruction_set.h"
 #include "base/mutex.h"
 #include "globals.h"
 #include "os.h"
@@ -79,6 +80,12 @@
   // Gets the path of the libcore dex file.
   static std::string GetLibCoreDexFileName();
 
+  // Returns bin directory which contains host's prebuild tools.
+  static std::string GetAndroidHostToolsDir();
+
+  // Returns bin directory which contains target's prebuild tools.
+  static std::string GetAndroidTargetToolsDir(InstructionSet isa);
+
  protected:
   static bool IsHost() {
     return !kIsTargetBuild;