Dir#input: don't overwrite license and vendor

Calling Dir#input overwrote #license and #vendor with default values.

Author: alxwr

lib/fpm/package/dir.rb

@@ -83,8 +83,8 @@ def input(path)
     # can include license data from themselves (rpms, gems, etc),
     # but to make sure a simple dir -> rpm works without having
     # to specify a license.
-    self.license = "unknown"
-    self.vendor = [ENV["USER"], Socket.gethostname].join("@")
+    self.license ||= "unknown"
+    self.vendor ||= [ENV["USER"], Socket.gethostname].join("@")
   ensure
     # Clean up any logger context we added.
     logger.remove("method")