Minor cleanup, #include's and unused vars.

Added compile-time warning to an old funky function.

lib/libc/stdio/findfp.c

@@ -127,6 +127,10 @@ __sfp()
  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
  * but documented historically for certain applications.  Bad applications.
  */
+__warn_references(f_prealloc, 
+	"warning: this program uses f_prealloc(), which is stupid.");
+
+void
 f_prealloc()
 {
 	register struct glue *g;

lib/libc/stdio/mktemp.c

@@ -40,6 +40,7 @@ static char sccsid[] = "@(#)mktemp.c	8.1 (Berkeley) 6/4/93";
 #include <fcntl.h>
 #include <errno.h>
 #include <stdio.h>
+#include <unistd.h>
 #include <ctype.h>
 
 static int _gettemp();

lib/libc/stdio/vsscanf.c

@@ -57,7 +57,6 @@ vsscanf(str, fmt, ap)
 	const char *fmt;
 	_BSD_VA_LIST_ ap;
 {
-	int ret;
 	FILE f;
 
 	f._flags = __SRD;