PRESUBMIT: exclude binaries from license check

The license check isn't going to find much of any valid text in these,
let alone text that matches our expected license headers. We keep a
LICENSE file in here instead. Disable the license check for the bin/
directory.

Fun fact: being fruitless doesn't stop pre-upload.py from spending a ton
of time doing regex comparisons on these binaries. For example, I had to
leave for lunch while Python was churning on a regex search over the 52
MB file in https://crrev.com/c/1954430 !

BUG=none
TEST=.../src/repohooks/pre-upload.py

Change-Id: If37c8f8e245dd987032302338eb0a492d52af143
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/intel-wifi-fw-dump/+/1954435
Tested-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
new file mode 100644
index 0000000..026a692
--- /dev/null
+++ b/PRESUBMIT.cfg
@@ -0,0 +1,4 @@
+[Hook Overrides]
+cros_license_check: true
+[Hook Overrides Options]
+cros_license_check: --exclude_regex=^bin\/