Only Windows doesn't have <sys/uio.h>.

This should probably be in libcutils instead, so code that needs to
care about Windows can use readv/writev.

Change-Id: I7c2ceec3f742cee0e44f69fd4c88459376bd0e08
diff --git a/liblog/uio.c b/liblog/uio.c
index 24a6507..f77cc49 100644
--- a/liblog/uio.c
+++ b/liblog/uio.c
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef HAVE_SYS_UIO_H
+#if defined(_WIN32)
 
 #include <log/uio.h>
 #include <unistd.h>
@@ -73,4 +73,4 @@
     return total;
 }
 
-#endif /* !HAVE_SYS_UIO_H */
+#endif