libwebp: Fix CVE-2023-1999

There exists a use after free/double free in libwebp. An attacker can
use the ApplyFiltersAndEncode() function and loop through to free
best.bw and assign best = trial pointer. The second loop will then
return 0 because of an Out of memory error in VP8 encoder, the pointer
is still assigned to trial and the AddressSanitizer will attempt a double free.

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2023-1999

Upstream patch:
https://github.com/webmproject/libwebp/commit/a486d800b60d0af4cc0836bf7ed8f21e12974129



Signed-off-by: Soumya <soumya.sambu@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>