The check that separates a rejected modify command line from an install
that ran and skipped a component watched for any Visual Studio installer
process by name. One already running for an unrelated reason would pass
for the one this step launches, putting the run back on the generic
"clang-cl was not installed" error it is meant to sharpen.
Snapshot the matching process ids before the launch and count only ones
that appear afterwards.
Zoltan Kochan
b4d19c87a1