test_gem_ext_builder.rb: fix wrong skip condition

* test/rubygems/test_gem_ext_builder.rb (test_build_extensions_extconf_bad):
  fix wrong skip condition by removing wrong expace, String#include?
  does not turn a string argument into a regexp.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47201 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rubygems/test_gem_ext_builder.rb

@@ -234,7 +234,7 @@ install:
     refute_path_exists @spec.gem_build_complete_path
 
     skip "Gem.ruby is not the name of the binary being run in the end" \
-      unless File.read(gem_make_out).include? "#{Regexp.escape Gem.ruby}:"
+      unless File.read(gem_make_out).include? "#{Gem.ruby}:"
 
     assert_match %r%#{Regexp.escape Gem.ruby}: No such file%,
                  File.read(gem_make_out)