test/socket/test_addrinfo.rb: Fix syntax error

Sorry!

test/socket/test_addrinfo.rb

@@ -369,7 +369,7 @@ class TestSocketAddrinfo < Test::Unit::TestCase
   def errors_addrinuse
     errs = [Errno::EADDRINUSE]
     # MinGW fails with "Errno::EACCES: Permission denied - bind(2) for 0.0.0.0:49721"
-    errs << Errno::EACCES if if /mingw/ =~ RUBY_PLATFORM
+    errs << Errno::EACCES if /mingw/ =~ RUBY_PLATFORM
     errs
   end