add pledge(2) to "mutool pages"

Index: source/tools/pdfpages.c
--- source/tools/pdfpages.c.orig
+++ source/tools/pdfpages.c
@@ -28,6 +28,9 @@
 #include "mupdf/fitz.h"
 #include "mupdf/pdf.h"
 
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 
@@ -212,6 +215,12 @@ int pdfpages_main(int argc, char **argv)
 
 	if (fz_optind == argc)
 		return infousage();
+
+	if (pledge("stdio rpath", NULL) == -1)
+	{
+		fprintf(stderr, "pledge: %s\n", strerror(errno));
+		exit(1);
+	}
 
 	ctx = fz_new_context(NULL, NULL, FZ_STORE_UNLIMITED);
 	if (!ctx)