SteamSocket::eraseFirstInputBytes() removes from the beginning
of std::vector, which is generally slow. If the buffer becomes
too big, which it may under a load, then the function will get
slow, which in turn will likely lead to the buffer getting even
bigger because of accumulated backlog.
The Buffer class is optimized for removal at the beginning,
so use it instead of std::vector, including some API additions
for it to be an in-place replacement where it's used.
Signed-off-by: Luboš Luňák <l.lunak@collabora.com>
Change-Id: I4cf7ec56c908c7d3df391dc3f8e230ad32abb162
897c5df270