patch block.c from openwrt fstools to add support for systems using ubifs instead of mtdblocks

ubifs_support.diff

diff --git a/block.c b/block.c
index a1609b4..a68d62a 100644
--- a/block.c
+++ b/block.c
@@ -791,6 +791,19 @@ static int main_hotplug(int argc, char **argv)
        return mount_device(find_block_info(NULL, NULL, path), 1);
 }
 
+static int find_block_ubi(char *name, char *part, int plen)
+{
+       // how to look this up?  ubinfo? - would be a lot of system calls...
+       if (!strcmp(name, "rootfs"))
+               snprintf(part, plen, "/dev/ubiblock0_0");
+       else if (!strcmp(name, "rootfs_data"))
+               snprintf(part, plen, "/dev/ubi0_1");
+       else
+               return -1;
+
+       return 0;
+}
+
 static int find_block_mtd(char *name, char *part, int plen)
 {
        FILE *fp = fopen("/proc/mtd", "r");
@@ -946,8 +959,11 @@ static int main_extroot(int argc, char **argv)
 
        find_block_mtd("rootfs", fs, sizeof(fs));
        if (!fs[0]) {
-               ERROR("extroot: unable to locate rootfs mtdblock\n");