Generate constants from <sys/mman.h>.

Pick up PROT_READ and friends from <sys/mman.h>.

Bug: http://b/38508369
Test: mma
Change-Id: Ie3077f7496a06f2671836ba0a1563f40124996fa
diff --git a/gen_constants-inl.h b/gen_constants-inl.h
index e439b3e..ea8c701 100644
--- a/gen_constants-inl.h
+++ b/gen_constants-inl.h
@@ -9,6 +9,7 @@
 #include <linux/termios.h>
 #include <stddef.h>
 #include <signal.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/resource.h>
 #include <sys/types.h>