Revert "omit tests related legacy provider"

This reverts commit 9b7543d.

The case not providing the legacy provider can happen not only in FreeBSD but
also in other platforms. The fix is addressed in the next commit.

Author: junaruga

test/openssl/test_provider.rb

@@ -12,8 +12,6 @@ def test_openssl_provider_name_inspect
   end
 
   def test_openssl_provider_names
-    omit if /freebsd/ =~ RUBY_PLATFORM
-
     with_openssl <<-'end;'
       legacy_provider = OpenSSL::Provider.load("legacy")
       assert_equal(2, OpenSSL::Provider.provider_names.size)
@@ -35,8 +33,6 @@ def test_unloaded_openssl_provider
   end
 
   def test_openssl_legacy_provider
-    omit if /freebsd/ =~ RUBY_PLATFORM
-
     with_openssl(<<-'end;')
       OpenSSL::Provider.load("legacy")
       algo = "RC4"