Fix up a few more implicit-function-declaration warnings on the BSDs

cde/programs/dthelp/dthelpprint/PrintTopics.c

@@ -49,6 +49,7 @@ $COPYRIGHT$:
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <unistd.h>
 #include <sys/stat.h>    /* for stat() */
 #if defined(sun)

cde/programs/dtlogin/server.c

@@ -47,6 +47,7 @@
  */
 
 # include	<sys/types.h>
+# include	<sys/socket.h>
 # include	<sys/signal.h>
 # include	<setjmp.h>
 # include       <errno.h>

cde/programs/dtterm/DtTermMain.c

@@ -60,6 +60,7 @@
 #include "TermPrimRenderP.h"
 #include "TermPrimLineDrawP.h"
 #include "TermPrimLineFontP.h"
+#include "TermPrimSetUtmp.h"
 #include "TermBufferP.h"
 #include "TermP.h"
 #include "TermParseTableP.h"