rbenv で Ruby 2.2.1 のインストールを試みましたが失敗しました。
Ubuntu 14.04 と ruby-build 20150303 を使っています。

$ rbenv install 2.2.1
Downloading ruby-2.2.1.tar.gz...
-> http://dqw8nmjcqpjn7.cloudfront.net/5a4de38068eca8919cb087d338c0c2e3d72c9382c804fb27ab746e6c7819ab28
Installing ruby-2.2.1...

BUILD FAILED (Ubuntu 14.04 using ruby-build 20150303)

Inspect or clean up the working tree at /tmp/ruby-build.20150304173607.22408
Results logged to /tmp/ruby-build.20150304173607.22408.log

Last 10 log lines:
compiling ossl_digest.c
compiling ossl_x509req.c
compiling ossl_asn1.c
installing default openssl libraries
linking shared-object psych.so
make[2]: Leaving directory `/tmp/ruby-build.20150304173607.22408/ruby-2.2.1/ext/psych'
linking shared-object openssl.so
make[2]: Leaving directory `/tmp/ruby-build.20150304173607.22408/ruby-2.2.1/ext/openssl'
make[1]: Leaving directory `/tmp/ruby-build.20150304173607.22408/ruby-2.2.1'
make: *** [build-ext] Error 2