Add android_mallopt to query MTE stack state

Bug: 244364391
Change-Id: Ie6267201f0c2e293b27c71cd160a2311c9de8091
diff --git a/libc/bionic/malloc_common_dynamic.cpp b/libc/bionic/malloc_common_dynamic.cpp
index 6c2f4d9..97e8d15 100644
--- a/libc/bionic/malloc_common_dynamic.cpp
+++ b/libc/bionic/malloc_common_dynamic.cpp
@@ -533,6 +533,14 @@
 
     return EnableGwpAsan(*reinterpret_cast<android_mallopt_gwp_asan_options_t*>(arg));
   }
+  if (opcode == M_MEMTAG_STACK_IS_ON) {
+    if (arg == nullptr || arg_size != sizeof(bool)) {
+      errno = EINVAL;
+      return false;
+    }
+    *reinterpret_cast<bool*>(arg) = atomic_load(&__libc_globals->memtag_stack);
+    return true;
+  }
   // Try heapprofd's mallopt, as it handles options not covered here.
   return HeapprofdMallopt(opcode, arg, arg_size);
 }