[coverage] Perform glob expansion so that the coverage script works on
fuzz targets.

The `coverage.py` file has instructions for how to generate coverage for
fuzz targets.

However, the command as-written fails because StandaloneFuzzTarget
expects to receive a list of inputs; it exits with an error if it's
given a pointer to a directory.

It's simple enough to simply append `/*` to the directory, but Python's
subprocess doesn't support glob expansion.

So, this commit (1) changes the instructions to the new command, and (2)
enables glob expansion on that command.

Bug: 1356583
Change-Id: I90345b05d5baf4d016551f5d2f39ec18a8535277
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4121294
Reviewed-by: Zhaoyang Li <zhaoyangli@chromium.org>
Commit-Queue: Julia Hansbrough <flowerhack@google.com>
Reviewed-by: Erik Staab <estaab@chromium.org>
Reviewed-by: Jeff Yoon <jeffyoon@google.com>
Cr-Commit-Position: refs/heads/main@{#1093525}

• tools/code_coverage/coverage.py[diff]