Pull fix for exFAT from original source

http://code.google.com/p/exfat/source/detail?r=336

Change-Id: Ie8453770a4dcb31283012550f28483ad88bdc267
diff --git a/exfat/libexfat/io.c b/exfat/libexfat/io.c
index 65df63a..1be028c 100644
--- a/exfat/libexfat/io.c
+++ b/exfat/libexfat/io.c
@@ -341,7 +341,7 @@
 	}
 	if (!ef->ro && !ef->noatime)
 		exfat_update_atime(node);
-	return size - remainder;
+	return MIN(size, node->size - offset) - remainder;
 }
 
 ssize_t exfat_generic_pwrite(struct exfat* ef, struct exfat_node* node,