Retry for EINTR (Fix for #16)

[j16sdiz]

No description provided.

[j16sdiz]

ref #16

[postwait]

write(2) will return -1 on error and set errno to EINTR...

I believe that should be

while(-1 == (_result = expr)) && errno == EINTR);

[postwait]

This line is unnecessary as you return result on the next line regardless.

[keithf4]

This is also changing the source of an external library we don't maintain

https://github.com/alanxz/rabbitmq-c

Be curious if this issue is handled better in a newer version of that library and we'd be better off trying to see if that could be incorporated. Would also possibly fix another open issue #5

[j16sdiz]

@keithf4

This is also changing the source of an external library we don't maintain
https://github.com/alanxz/rabbitmq-c

I have checked @alanxz 's version before my change -- he have that fixed already.
but they have too many different that may need to rewrite those glue.

[j16sdiz]

I have another branch https://github.com/j16sdiz/pg_amqp/tree/librabbitmq-0.4 that use 0.4 from upstream.
It is free of compile error, but I am not confident it would work correctly.