[klibc] Add support for __sum* types

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/usr/include/sys/types.h b/usr/include/sys/types.h
index 41cc634..6780ed1 100644
--- a/usr/include/sys/types.h
+++ b/usr/include/sys/types.h
@@ -96,6 +96,10 @@
 typedef uint64_t __bitwise __le64;
 typedef uint64_t __bitwise __be64;
 
+typedef uint16_t __sum16;
+typedef uint32_t __sum32;
+typedef uint64_t __sum64;
+
 /*
  * Some headers seem to require this...
  */