#284 prevent padding spec from exceeding limit

[Josh Coalson]

libFLAC and flac need checks where padding is specified or merged to make sure the size does not exceed the metadata block size limit of 2^24 bytes.

[Erik]

Fixed in:

commit 27e00c8be0f1f4de94336f3ec8f12942e01a8cca
Author: Erik de Castro Lopo <erikd@mega-nerd.com>
Date:   Sat Jan 9 10:35:23 2016 +1100

flac/encode.c: Limit padding size

This prevents a too large padding value overflowing the block length.

Patch-from: lvqcl <lvqcl.mail@gmail.com>
Closes: https://sourceforge.net/p/flac/bugs/284/