Merge memory checking functionality from sandbox

Change-Id: I304c789a752c9f4af4944ca14b9bf1e7644da15a
diff --git a/libc/bionic/malloc_debug_leak.c b/libc/bionic/malloc_debug_leak.c
index 7b8822c..e11606d 100644
--- a/libc/bionic/malloc_debug_leak.c
+++ b/libc/bionic/malloc_debug_leak.c
@@ -629,3 +629,12 @@
     }
     return base;
 }
+
+/* Initializes malloc debugging framework.
+ * See comments on MallocDebugInit in malloc_debug_common.h
+ */
+int malloc_debug_initialize(void)
+{
+    // We don't really have anything that requires initialization here.
+    return 0;
+}