Bump third_party/libwebsockets/repo from `c57c239` to `626f881` #5550

Job	Run time
Build on Darwin (clang, simulated)	56m 7s
Build on Linux (fake, gcc_release, clang, simulated)	1h 2m 5s
Build on Linux (coverage)	15m 15s
Build on Linux (gcc_debug)	1h 4m 13s
Build on Linux (python_lib)	23m 3s
Build on Linux (python lighting-app)	6m 50s
	3h 47m 33s

Provide feedback