Add an android_mallopt for controlling the heap tagging level.

This doesn't add any functionality for now, but there are
a couple of changes in flight that will want to add enumerators
to the mallopt, so let's give them a place to add them.

Bug: 135772972
Bug: 135754954
Change-Id: I6e810020f66070e844500c6fa99b703963365659
diff --git a/libc/bionic/malloc_common.cpp b/libc/bionic/malloc_common.cpp
index a0da3db..30c9cc7 100644
--- a/libc/bionic/malloc_common.cpp
+++ b/libc/bionic/malloc_common.cpp
@@ -41,6 +41,7 @@
 #include <private/bionic_config.h>
 #include <platform/bionic/malloc.h>
 
+#include "heap_tagging.h"
 #include "malloc_common.h"
 #include "malloc_limit.h"
 
@@ -275,6 +276,9 @@
   if (opcode == M_SET_ALLOCATION_LIMIT_BYTES) {
     return LimitEnable(arg, arg_size);
   }
+  if (opcode == M_SET_HEAP_TAGGING_LEVEL) {
+    return SetHeapTaggingLevel(arg, arg_size);
+  }
   errno = ENOTSUP;
   return false;
 }