the underlying IO become readable or writable if the error was
SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE. [ruby-dev:25795]
* ext/openssl/ossl_ssl.c (ossl_ssl_read, ossl_ssl_write): ditto.
* ext/openssl/lib/openssl/buffering.rb
(Buffering#consume_rbuf): pointless eof flag resetting is deleted.
(Buffering#read): should return an empty string if the specified
size is zero.
(Buffering#readpartial): new method.
(Buffering#readline): fix typo.
(Buffering#getc): return the first character of string correctly.
(Buffering#readchar): fix typo.
(Buffering#eof?): should read again it the input buffer is empty.
(Buffering#do_write): should rescue Errno::EAGAIN.
(Buffering#puts): use "\n" as the output field separator.
* ext/openssl/extconf.rb: get rid of GNUmakefile generation.
* text/openssl/test_pair.rb: test for IO like methods.
* test/ruby/ut_eof.rb: test about empty file.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8081 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
