minigbm: add spew on IOCTL failures.

Having spew on errors would have made debugging the Netflix
double fd close more obvious.

BUG=chromium:462459, chromium:464628
TEST=Builds for link, tegra, nyan.

Change-Id: I050794fbca8e9291752e52119751847ffcacd798
Reviewed-on: https://chromium-review.googlesource.com/265065
Reviewed-by: Ilja Friedel <ihf@chromium.org>
Commit-Queue: Ilja Friedel <ihf@chromium.org>
Tested-by: Ilja Friedel <ihf@chromium.org>
6 files changed