bspatch: Fix missing header <sys/types.h> for u_char

Fixes http://autobuild.buildroot.net/results/31a/31a837cf6e34b02dce498f2b12e40d6d16a5a8e6/

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>

diff -purN bsdiff-4.3.orig/bspatch.c bsdiff-4.3/bspatch.c
--- bsdiff-4.3.orig/bspatch.c	2015-04-30 13:47:26.485903359 +0200
+++ bsdiff-4.3/bspatch.c	2015-04-30 13:48:14.808908672 +0200
@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/b
 #include <err.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/types.h>

 static off_t offtin(u_char *buf)
 {