Reduce OpenSSL::Buffering#do_write overhead #1297

Job	Run time
openssl-1.0.2u	53s
openssl-1.1.0l	1m 0s
openssl-1.1.1w	56s
openssl-3.0.15	1m 5s
openssl-3.1.7	57s
openssl-3.2.3	58s
openssl-3.3.2	1m 3s
openssl-3.4.0	57s
openssl-master	3m 52s
libressl-3.1.5	1m 1s
libressl-3.2.7	1m 1s
libressl-3.3.6	1m 2s
libressl-3.4.3	1m 1s
libressl-3.5.3	1m 2s
libressl-3.6.3	1m 12s
libressl-3.7.3	56s
libressl-3.8.4	1m 3s
libressl-3.9.2	57s
libressl-4.0.0	1m 2s
openssl-3.0.15 with fips provider	58s
openssl-3.1.7 with fips provider	57s
openssl-3.2.3 with fips provider	49s
openssl-3.3.2 with fips provider	56s
openssl-3.4.0 with fips provider	58s
openssl-master with fips provider	3m 38s
openssl-3.4.0 without legacy provider	57s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.7	59s
ubuntu-22.04 3.0	54s
ubuntu-22.04 3.1	1m 1s
ubuntu-22.04 3.2	1m 3s
ubuntu-22.04 3.3	1m 2s
ubuntu-22.04 3.4	1m 12s
ubuntu-22.04 head	1m 8s
ubuntu-22.04 truffleruby	1m 38s
ubuntu-22.04 truffleruby-head	1m 54s
ubuntu-20.04 2.7	1m 1s
ubuntu-20.04 3.0	57s
ubuntu-20.04 3.1	58s
ubuntu-20.04 3.2	1m 2s
ubuntu-20.04 3.3	56s
ubuntu-20.04 3.4	1m 6s
ubuntu-20.04 head	1m 4s
ubuntu-20.04 truffleruby	1m 42s
ubuntu-20.04 truffleruby-head	1m 43s
macos-latest 2.7	52s
macos-latest 3.0	39s
macos-latest 3.1	41s
macos-latest 3.2	39s
macos-latest 3.3	41s
macos-latest 3.4	1m 4s
macos-latest head	43s
macos-latest truffleruby	1m 6s
macos-latest truffleruby-head	1m 8s
windows-latest 2.7	4m 25s
windows-latest 3.0	5m 14s
windows-latest 3.1	4m 33s
windows-latest 3.2	3m 48s
windows-latest 3.3	4m 7s
windows-latest 3.4	8s
windows-latest head	4m 45s
windows-latest ucrt	4m 30s
windows-latest mswin	3m 49s
	1h 35m 26s

Provide feedback