Fix platform-dependent or fragile test cases added by r59734. This is a
combined patch of the three commits below:

	4fc17977350a test/test_fips: skip if setting FIPS mode fails
	b25179fbeebf test/test_asn1: fix possible failure in test_utctime
	8ed81ff4b0a8 test/test_pair: fix test_write_nonblock{,_no_exceptions}

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59751 b2dd03c8-39d4-4d8f-98ff-823fe69b080e