netbsd-7 build error?

[Havard Eidnes <he%NetBSD.org@localhost>]

Hi,

I just updated one of my source trees to netbsd-7, and did a
fresh rebuild (empty obj and dest, host oldish 7.1_STABLE), but
got:

    compile  libc/compat___msgctl13.o
In file included from /usr/src/lib/libc/compat/sys/compat___msgctl13.c:48:0:
/usr/src/sys/compat/sys/msg.h: In function '__native_to_msqid_ds13':
/usr/src/sys/compat/sys/msg.h:111:2: error: implicit declaration of function 'memset' [-Werror=implicit-function-declaration]
  memset(omsqbuf, 0, sizeof(*omsqbuf));
  ^
/usr/src/sys/compat/sys/msg.h:111:2: error: incompatible implicit declaration of built-in function 'memset' [-Werror]
/usr/src/sys/compat/sys/msg.h: In function '__native_to_msqid_ds14':
/usr/src/sys/compat/sys/msg.h:153:2: error: incompatible implicit declaration of built-in function 'memset' [-Werror]
  memset(omsqbuf, 0, sizeof(*omsqbuf));
  ^
cc1: all warnings being treated as errors

*** Failed target:  compat___msgctl13.o

I see the auto-build has not seen this error.  Locally I did

Index: sys/compat/sys/msg.h
===================================================================
RCS file: /cvsroot/src/sys/compat/sys/msg.h,v
retrieving revision 1.4.40.1
diff -u -r1.4.40.1 msg.h
--- sys/compat/sys/msg.h        2 Jan 2019 15:25:29 -0000       1.4.40.1
+++ sys/compat/sys/msg.h        3 Jan 2019 15:42:37 -0000
@@ -22,6 +22,7 @@
 #ifndef _COMPAT_SYS_MSG_H_
 #define _COMPAT_SYS_MSG_H_
 
+#include <string.h>
 #include <compat/sys/ipc.h>
 /*
  * Old message queue data structure used before NetBSD 1.5.

Anyone have any guess why I saw this build error but it's not
seen in the autobuild?

- Håvard