FAST parser: Wait for socket data in a 'raw' mode

We should be aware of non-blocking sockets and wait
for data to come before reading bytes. There is no
performance consideration in a 'raw'-mode so waiting
is acceptable here

$ ./tools/fast/fast_parser -p raw -m xxx.xxx.xxx.xxx:xxx -l xxx.xxx.xxx.xxx -o file
Parser: Cannot read data (Resource temporarily unavailable)

Reported-by: Marek Sulovsky <mareksulovsky@gmail.com>
Signed-off-by: Marat Stanichenko <mstanichenko@gmail.com>