vvfat: fix a file descriptor leak

Fix a file descriptor leak, reported by cppcheck:
[/src/qemu/block/vvfat.c:759]: (error) Resource leak: dir

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/block/vvfat.c b/block/vvfat.c
index 26dd474..fe568fe 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -756,6 +756,7 @@
         if (st.st_size > 0x7fffffff) {
 	    fprintf(stderr, "File %s is larger than 2GB\n", buffer);
 	    free(buffer);
+            closedir(dir);
 	    return -2;
         }
 	direntry->size=cpu_to_le32(S_ISDIR(st.st_mode)?0:st.st_size);