Ben Gamari authored Nov 01, 2015 and Ben Gamari committed Nov 01, 2015

Previously the eventlog flush code would fail if `fwrite` wrote less
than the requested amount. Like all Unix stream I/O operations, however,
`fwrite` isn't guaranteed to write the entire buffer. Here we loop as
long as `fwrite` succeeds in writing anything.

Fixes #11041.

Test Plan: Validate with eventlog

Reviewers: austin, simonmar

Reviewed By: simonmar

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1415

GHC Trac Issues: #11041