lavc: move put_bits_left in put_bits.h
wmapro: make sure there is room to store the current packet

Prevent horrid and hard to trace struct overwrite.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
wmapro: return early on unsupported condition

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
wmapro: check num_vec_coeffs against the actual available buffer

Prevent yet another buffer overwrite.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org