Reduce OpenSSL::Buffering#do_write overhead #1307

Job	Run time
openssl-1.0.2u	52s
openssl-1.1.0l	55s
openssl-1.1.1w	54s
openssl-3.0.15	58s
openssl-3.1.7	57s
openssl-3.2.3	56s
openssl-3.3.2	1m 4s
openssl-3.4.0	56s
openssl-master	3m 54s
libressl-3.1.5	53s
libressl-3.2.7	1m 7s
libressl-3.3.6	1m 7s
libressl-3.4.3	1m 5s
libressl-3.5.3	1m 0s
libressl-3.6.3	58s
libressl-3.7.3	55s
libressl-3.8.4	1m 4s
libressl-3.9.2	55s
libressl-4.0.0	1m 2s
openssl-3.0.15 with fips provider	50s
openssl-3.1.7 with fips provider	52s
openssl-3.2.3 with fips provider	49s
openssl-3.3.2 with fips provider	52s
openssl-3.4.0 with fips provider	50s
openssl-master with fips provider	3m 41s
openssl-3.4.0 without legacy provider	57s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.7	58s
ubuntu-22.04 3.0	55s
ubuntu-22.04 3.1	1m 1s
ubuntu-22.04 3.2	59s
ubuntu-22.04 3.3	58s
ubuntu-22.04 3.4	1m 0s
ubuntu-22.04 head	1m 4s
ubuntu-22.04 truffleruby	1m 32s
ubuntu-22.04 truffleruby-head	1m 56s
ubuntu-20.04 2.7	1m 1s
ubuntu-20.04 3.0	58s
ubuntu-20.04 3.1	1m 2s
ubuntu-20.04 3.2	1m 0s
ubuntu-20.04 3.3	56s
ubuntu-20.04 3.4	54s
ubuntu-20.04 head	55s
ubuntu-20.04 truffleruby	1m 27s
ubuntu-20.04 truffleruby-head	1m 41s
macos-latest 2.7	1m 23s
macos-latest 3.0	33s
macos-latest 3.1	38s
macos-latest 3.2	41s
macos-latest 3.3	39s
macos-latest 3.4	43s
macos-latest head	49s
macos-latest truffleruby	57s
macos-latest truffleruby-head	1m 9s
windows-latest 2.7	5m 35s
windows-latest 3.0	3m 48s
windows-latest 3.1	4m 32s
windows-latest 3.2	4m 2s
windows-latest 3.3	4m 50s
windows-latest 3.4	4m 52s
windows-latest head	4m 7s
windows-latest ucrt	3m 56s
windows-latest mswin	3m 16s
	1h 37m 13s

Provide feedback