Patchs from Jeff Garzik <jgarzik@mandrakesoft.com> to cleanup

warnings with glibc 2.2 and use always use xfopen
 -Erik

miscutils/dc.c

@@ -2,6 +2,7 @@
 #include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <math.h>
 #include "busybox.h"

miscutils/mktemp.c

@@ -24,6 +24,7 @@
 
 #include <stdio.h>
 #include <errno.h>
+#include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include "busybox.h"

miscutils/mt.c

@@ -1,6 +1,7 @@
 /* vi: set sw=4 ts=4: */
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/mtio.h>
 #include <sys/fcntl.h>
 #include "busybox.h"