bitcoin/bitcoin — pull request #1786 by jgarzik (2012-09-05 03:28:42+00:00)
Title: select()'s first argument should be zero, if no file descriptors are selected

The most portable invocation for the zero-fds case, a widely used
portable hack for sleeping, generally involves passing NULL arguments
when the fd sets are unused. This form is used here.

Intended to supercede #1772.