Modify TestSSL#test_read_and_write to handle partial sysreads
from github: https://github.com/ruby/ruby/pull/204
((*SSLSocket#sysread can return fewer bytes than you request. This test does client reads and writes and server reads and writes concurrently, which means on a parallel-threaded implementation like JRuby there's a chance the client side will see partial data come from sysread.
My change here ensures that the sysread has read everything written before doing comparisons, allowing for partial sysread results.*))