Print allocator version in the malloc_info test.

It's a simple addition that is helpful verifying the allocator being
used during test runs.

Test: All unit tests pass.
Change-Id: If2c4048bb0a4b628ab3ce3c2b4a11c3be3361627
diff --git a/tests/malloc_test.cpp b/tests/malloc_test.cpp
index 3f1ba79..4d5a569 100644
--- a/tests/malloc_test.cpp
+++ b/tests/malloc_test.cpp
@@ -466,6 +466,7 @@
     // Do not verify output for debug malloc.
     ASSERT_TRUE(version == "debug-malloc-1") << "Unknown version: " << version;
   }
+  printf("Allocator version: %s\n", version.c_str());
 #endif
 }