test TestUnixSocketThreadedServer2 blocks for large buffers

[marcotessarotto]

set:
const ssize_t bufferSize = 4096 * 16 * 16;
then test is stuck in a loop of:
[BaseClient::read] errno == EAGAIN || errno == EWOULDBLOCK

[marcotessarotto]

there seems to be an issue with "large" buffers when using unix sockets.