Fix crash when path to a toml file is given

Fixes a programming error introduced in b284d61ee7, the
variables were not defined.

rust2rpm/__main__.py

@@ -125,6 +125,9 @@ def local_toml(toml, version):
         doc_files = get_doc_files(toml)
         license_files = get_license_files(toml)
         toml = os.path.join(toml, "Cargo.toml")
+    else:
+        doc_files = []
+        license_files = []
 
     return toml, None, version, doc_files, license_files