Only the Mac doesn't have open_memstream.

We should probably move this into art, since they're the only people using it.

Bug: 17164505
Change-Id: I67b8f0cbad4c6368d4424e6979d6b044dd36aa37
diff --git a/libcutils/open_memstream.c b/libcutils/open_memstream.c
index 5b4388a..1c37321 100644
--- a/libcutils/open_memstream.c
+++ b/libcutils/open_memstream.c
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef HAVE_OPEN_MEMSTREAM
+#if defined(__APPLE__)
 
 /*
  * Implementation of the POSIX open_memstream() function, which Linux has
@@ -378,4 +378,4 @@
 
 #endif
 
-#endif /*!HAVE_OPEN_MEMSTREAM*/
+#endif /* __APPLE__ */