libcutils should #include <sys/sysmacros.h>

Bug: https://github.com/android-ndk/ndk/issues/398
Test: builds
Change-Id: I8ca21a74e2856fde09c284aee1343c627d8381e6
diff --git a/libcutils/ashmem-dev.c b/libcutils/ashmem-dev.c
index 92717c0..b4abb79 100644
--- a/libcutils/ashmem-dev.c
+++ b/libcutils/ashmem-dev.c
@@ -28,6 +28,7 @@
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
+#include <sys/sysmacros.h>
 #include <sys/types.h>
 #include <unistd.h>