Fix is_clang python3 encoding errors
Fix is_clang python3 encoding errors

python 2.7 subprocess.check_output:

  "Run command with arguments and return its output as a byte string."

python 3 ubprocess.check_output:

  "By default, this function will return the data as encoded bytes."

Using a 'b' prefix seems to cover both cases.

Change-Id: Ie2d90bc93d0e98a723a262fae63fe538137812c5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299382
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@google.com>
Reviewed-by: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>

google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia