win: Let reorder-imports.py fail if its invocation of swapimport.exe fails.

win: Let reorder-imports.py fail if its invocation of swapimport.exe fails.

At first I didn't hook up the script correctly in the gn build.  swapimport.exe
printed

  ERROR:swapimport_app.cc(214)] Path does not exist: ../../chrome/initialexe\chrome.exe

but that didn't make the build fail -- instead, it silently left the old
chrome.exe (from prior builds) around.  Make it so that swapimport.exe failing
makes the build fail.

BUG=505062, 512599
Committed: https://crrev.com/7c3c949a348b5f6e47eea84f5d533918d816fba4
Cr-Commit-Position: refs/heads/master@{#350482}

[Nico, 2015-09-24 03:28:49]

thakis@chromium.org changed reviewers:
+ caitkp@chromium.org, robertshield@chromium.org

[Nico, 2015-09-24 03:28:50]

whoops :-)

[robertshield, 2015-09-24 03:34:10]

ick, that was a disaster waiting to happen.. thank goodness we had the unit test
too. 

thanks for the fix

lgtm

[robertshield, 2015-09-24 03:34:16]

The CQ bit was checked by robertshield@chromium.org

[commit-bot: I haz the power, 2015-09-24 03:34:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1363243002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1363243002/1

[commit-bot: I haz the power, 2015-09-24 05:08:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-24 05:09:39]

Patchset 1 (id:??) landed as
https://crrev.com/7c3c949a348b5f6e47eea84f5d533918d816fba4
Cr-Commit-Position: refs/heads/master@{#350482}