daklib/checks.py: No longer set LINTIAN_COLL_UNPACKED_SKIP_SIG=1

lintian passes --no-check to dpkg-source by default since 2.5.15. There
is no longer a need to set undocumented environment variables.

daklib/checks.py

@@ -662,7 +662,7 @@ class LintianCheck(Check):
             if user is not None:
                 cmd.extend(['sudo', '-H', '-u', user])
 
-            cmd.extend(['LINTIAN_COLL_UNPACKED_SKIP_SIG=1', '/usr/bin/lintian', '--show-overrides', '--tags-from-file', temp_filename, changespath])
+            cmd.extend(['/usr/bin/lintian', '--show-overrides', '--tags-from-file', temp_filename, changespath])
             output = daklib.daksubprocess.check_output(cmd, stderr=subprocess.STDOUT)
         except subprocess.CalledProcessError as e:
             result = e.returncode