In our local tree we have this change to work around the fact that
FreeBSD doesn't provide a getline() prototype unless _WITH_GETLINE is
defined before stdio.h is included.  It would be nice if some variant of
this could make it in to mandoc.

Thanks,
Brooks

commit f1e1737d27fe77dc6f7709aee31911e30684d653
Author: Robert N. M. Watson <robert.watson@cl.cam.ac.uk>
Date:   Wed Aug 16 22:58:19 2017 +0100

    getline(3) now requires defining _WITH_GETLINE before including stdio.h.
    Otherwise, getline() comes without function prototypes, which is not OK
    on CHERI.
    
    (Upstreaming candidate.)

diff --git a/contrib/mdocml/mandocdb.c b/contrib/mdocml/mandocdb.c
index b9e4fb1c813..4f064d88fde 100644
--- a/contrib/mdocml/mandocdb.c
+++ b/contrib/mdocml/mandocdb.c
@@ -40,6 +40,7 @@
 #endif
 #include <stdarg.h>
 #include <stddef.h>
+#define        _WITH_GETLINE
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>