go/loader: limit concurrency of I/O operations during parsing

This is a putative fix for the file descriptor exhaustion problem
described in https://github.com/golang/go/issues/10306.

Change-Id: If603fb9bbaec1b53f6b44d15b2c202e4670035ce
Reviewed-on: https://go-review.googlesource.com/8421
Reviewed-by: Matt Joiner <anacrolix@gmail.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
1 file changed