It looks like PNaCl actually depends on MSVC's presance, but doesn't
actually run any compile steps with it (instead using clang). That means
that mspdbsrv never actually runs during their build, and then the
taskkill fails.

R=hinoka@chromium.org, tandrii@chromium.org

Bug: 861512
Change-Id: I004d28f198224adaf16b1d3f14401b0d2a7d700b
Reviewed-on: https://chromium-review.googlesource.com/1232885Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>