Copy vcruntime*.dll to the build directory for the VS2015 builds.

It looks like it's needed at least for the PGI instrumented builds (my guess is that pgort140.dll has a dependency on this).

R=scottmg@chromium.org
BUG=440500

Review URL: https://codereview.chromium.org/1532163002

Cr-Original-Commit-Position: refs/heads/master@{#365875}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7cebe2199a4ed5b97f00369b54788216e7f399d6

vs_toolchain.py

@@ -104,7 +104,7 @@ def _CopyRuntime2013(target_dir, source_dir, dll_pattern):
 def _CopyRuntime2015(target_dir, source_dir, dll_pattern):
   """Copy both the msvcp and vccorlib runtime DLLs, only if the target doesn't
   exist, but the target directory does exist."""
-  for file_part in ('msvcp', 'vccorlib'):
+  for file_part in ('msvcp', 'vccorlib', 'vcruntime'):
     dll = dll_pattern % file_part
     target = os.path.join(target_dir, dll)
     source = os.path.join(source_dir, dll)