Use more shorter filenames to avoid sockaddr_un size limitation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50217 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_file_exhaustive.rb

@@ -54,7 +54,7 @@ class TestFileExhaustive < Test::Unit::TestCase
   end
 
   def make_tmp_filename(prefix)
-    "#{@dir}/#{prefix}.#{$$}.test"
+    "#{@dir}/#{prefix}.test"
   end
 
   def test_path