common.mk: update unicode files every times

* common.mk (update-unicode): remove -e option to force update
  every builds.

* tool/downloader.rb (Downloader.download): return if ims is nil
  and target file is existing.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48056 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

common.mk

@@ -1092,7 +1092,7 @@ update-gems: PHONY
 update-unicode: PHONY
 	$(ECHO) Downloading Unicode data files...
 	$(Q) $(BASERUBY) -C "$(srcdir)/enc/unicode/data" \
-	    ../../../tool/downloader.rb -e unicode \
+	    ../../../tool/downloader.rb unicode \
 	    UnicodeData.txt CompositionExclusions.txt NormalizationTest.txt
 
 enc/unicode/data/UnicodeData.txt \

tool/downloader.rb

@@ -54,7 +54,7 @@ class Downloader
   #            'UnicodeData.txt', 'enc/unicode/data'
   def self.download(url, name, dir = nil, ims = true)
     file = dir ? File.join(dir, name) : name
-    # return true if ims.nil? and File.exist?(file)
+    return true if ims.nil? and File.exist?(file)
     url = URI(url)
     if $VERBOSE
       $stdout.print "downloading #{name} ... "