Bump third_party/libwebsockets/repo from `c57c239` to `626f881` #413

Job	Run time
Build on Darwin (clang, python_lib, simulated)	2h 7m 42s
Build on Linux (coverage)	15m 25s
Build on Linux (fake, gcc_release, clang, simulated)	1h 59m 57s
Build on Linux (gcc_debug)	1h 2m 30s
Build on Linux (python lighting-app)	13m 28s
Build on Linux (python_lib)	23m 26s
	6h 2m 28s

Provide feedback