Fix errno typo in env_chromium.cc

CL [1] removed usage of readdir_r(), but in doing so added a bug where
errno should have been saved_errno.

[1] https://chromium-review.googlesource.com/c/599120

BUG=751812
R=jsbell@chromium.org

Change-Id: I5bdc554e62052d050be076bea3eddee9a6850212
Reviewed-on: https://chromium-review.googlesource.com/602697
Reviewed-by: Chris Mumford <cmumford@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#492413}
1 file changed