msg: make vmsg and vfmsg declarations match implementation

The 'suf' parameter was a late addition to the msg implementation.
I forgot to add it to the declarations in the header file.

Include msg.h in msg.c so the compiler will flag any future
mismatches.

msg.c

@@ -4,6 +4,8 @@
 #include <stdlib.h>    /* malloc, exit, free */
 #include <sys/errno.h> /* errno    */
 
+#include "msg.h"
+
 void vfmsg(FILE *f,
         const char *pre, const char *fmt, const char *suf,
         va_list ap) {

msg.h

@@ -1,9 +1,11 @@
 #include <stdarg.h>
 #include <stdio.h>
 
-void vfmsg(FILE *f, const char *pre, const char *fmt, va_list ap);
+void vfmsg(FILE *f,
+        const char *pre, const char *fmt, const char *suf,
+        va_list ap);
 extern FILE *msgout;
-void vmsg(const char *pre, const char *fmt, va_list ap);
+void vmsg(const char *pre, const char *fmt, const char *suf, va_list ap);
 void msg(const char *fmt, ...);
 void warn(const char *fmt, ...);
 void die(int ev, const char *fmt, ...);