add OpenBSD pledge(2) support using -DUSE_PLEDGE

stagit.c

@@ -64,6 +64,14 @@ static char lastoidstr[GIT_OID_HEXSZ + 2]; /* id + newline + nul byte */
 static FILE *rcachefp, *wcachefp;
 static const char *cachefile;
 
+#ifndef USE_PLEDGE
+int
+pledge(const char *promises, const char *paths[])
+{
+	return 0;
+}
+#endif
+
 void
 deltainfo_free(struct deltainfo *di)
 {
@@ -1033,6 +1041,9 @@ main(int argc, char *argv[])
 	size_t n;
 	int i, fd;
 
+	if (pledge("stdio rpath wpath cpath", NULL) == -1)
+		err(1, "pledge");
+
 	for (i = 1; i < argc; i++) {
 		if (argv[i][0] != '-') {
 			if (repodir)