Fix UnboundLocalError in CheckLicense.

`current_year` wasn't initialized if `licence_re` is set.
See e.g. https://ci.chromium.org/b/8799737896715431809

R=brucedawson@chromium.org, iannucci@chromium.org
BUG=1098010

Change-Id: Idb1a320af7f4790f2dac0fba7a62e2990a3664e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3969027
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Harald Alvestrand <hta@chromium.org>

presubmit_canned_checks.py

@@ -639,6 +639,8 @@ def CheckLicense(input_api, output_api, license_re=None, project_name=None,
   if license_re and license_re == '.*':
     return []
 
+  current_year = int(input_api.time.strftime('%Y'))
+
   if license_re:
     new_license_re = license_re
   else:
@@ -647,7 +649,6 @@ def CheckLicense(input_api, output_api, license_re=None, project_name=None,
     # Accept any year number from 2006 to the current year, or the special
     # 2006-20xx string used on the oldest files. 2006-20xx is deprecated, but
     # tolerated on old files. On new files the current year must be specified.
-    current_year = int(input_api.time.strftime('%Y'))
     allowed_years = (str(s) for s in reversed(range(2006, current_year + 1)))
     years_re = '(' + '|'.join(allowed_years) + '|2006-2008|2006-2009|2006-2010)'