ART: Use __ANDROID__ instead of HAVE_ANDROID_OS

Use the proper define.

Change-Id: I71e291ac25f5d5f0187ac9b6ef2d6872f19e6085
diff --git a/runtime/gc/allocator/dlmalloc.h b/runtime/gc/allocator/dlmalloc.h
index 0e91a43..0558921 100644
--- a/runtime/gc/allocator/dlmalloc.h
+++ b/runtime/gc/allocator/dlmalloc.h
@@ -35,7 +35,7 @@
 #include "../../bionic/libc/upstream-dlmalloc/malloc.h"
 #pragma GCC diagnostic pop
 
-#ifdef HAVE_ANDROID_OS
+#ifdef __ANDROID__
 // Define dlmalloc routines from bionic that cannot be included directly because of redefining
 // symbols from the include above.
 extern "C" void dlmalloc_inspect_all(void(*handler)(void*, void *, size_t, void*), void* arg);