Fix Darwin build.

Test: None because Darwin
Bug: None
Change-Id: Ibf4efff9726b937d664d15edd8a68ad23a6342fb
diff --git a/Android.bp b/Android.bp
index f2a671e..5a06d8c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -85,7 +85,7 @@
         darwin: {
             // libcxxabi really doesn't like the non-LLVM assembler on Darwin
             asflags: ["-integrated-as"],
-            cflags: ["-integrated-as"],
+            cflags: ["-integrated-as", "-D_LIBCPP_DISABLE_AVAILABILITY"],
             cppflags: ["-integrated-as"],
         },
         linux_bionic: {