tflite: dbg: Print character in single-quoted form

BUG=b:305999697
TEST=bazel run --config=host_clang '//common:dbg_test'

Change-Id: Iaa83b3bf9fa3fe31a42a8e54e1e68846da35fce4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/tflite/+/5379948
Reviewed-by: Tommy Chiang <ototot@google.com>
Commit-Queue: Tommy Chiang <ototot@google.com>
Auto-Submit: Shik Chen <shik@chromium.org>
Tested-by: Shik Chen <shik@chromium.org>