android_mallopt: opcode preprocess define + missing header

Addressing Elliott's remaining comments on the android_mallopt change.
Intending to let this get merged in normally (should be clean).

Test: blueline-userdebug still builds.
Change-Id: I4f00191091b8af367f84d087432a5af5f83036ee
diff --git a/libc/private/bionic_malloc.h b/libc/private/bionic_malloc.h
index 0e8a911..a9fa22d 100644
--- a/libc/private/bionic_malloc.h
+++ b/libc/private/bionic_malloc.h
@@ -28,11 +28,16 @@
 
 #pragma once
 
+#include <stdbool.h>
+
 // Opcodes for android_mallopt.
 
 // Marks the calling process as a profileable zygote child, possibly
 // initializing profiling infrastructure.
-#define  M_INIT_ZYGOTE_CHILD_PROFILING 1
+enum {
+  M_INIT_ZYGOTE_CHILD_PROFILING = 1,
+#define M_INIT_ZYGOTE_CHILD_PROFILING M_INIT_ZYGOTE_CHILD_PROFILING
+};
 
 // Manipulates bionic-specific handling of memory allocation APIs such as
 // malloc. Only for use by the Android platform itself.