Reduce OpenSSL::Buffering#do_write overhead #1299

Job	Run time
openssl-1.0.2u	51s
openssl-1.1.0l	52s
openssl-1.1.1w	53s
ruby-versions / Generate Ruby versions	2s
openssl-3.0.15	1m 6s
openssl-3.1.7	55s
openssl-3.2.3	58s
openssl-3.3.2	58s
openssl-3.4.0	56s
openssl-master	3m 47s
libressl-3.1.5	53s
libressl-3.2.7	1m 3s
libressl-3.3.6	1m 5s
libressl-3.4.3	59s
libressl-3.5.3	1m 6s
libressl-3.6.3	59s
libressl-3.7.3	1m 2s
libressl-3.8.4	57s
libressl-3.9.2	58s
libressl-4.0.0	58s
openssl-3.0.15 with fips provider	50s
openssl-3.1.7 with fips provider	49s
openssl-3.2.3 with fips provider	48s
openssl-3.3.2 with fips provider	51s
openssl-3.4.0 with fips provider	56s
openssl-master with fips provider	3m 49s
openssl-3.4.0 without legacy provider	57s
ubuntu-22.04 2.7	59s
ubuntu-22.04 3.0	52s
ubuntu-22.04 3.1	1m 3s
ubuntu-22.04 3.2	1m 0s
ubuntu-22.04 3.3	58s
ubuntu-22.04 3.4	1m 0s
ubuntu-22.04 head	58s
ubuntu-22.04 truffleruby	1m 35s
ubuntu-22.04 truffleruby-head	1m 45s
ubuntu-20.04 2.7	1m 3s
ubuntu-20.04 3.0	56s
ubuntu-20.04 3.1	56s
ubuntu-20.04 3.2	1m 0s
ubuntu-20.04 3.3	58s
ubuntu-20.04 3.4	1m 1s
ubuntu-20.04 head	56s
ubuntu-20.04 truffleruby	1m 34s
ubuntu-20.04 truffleruby-head	1m 46s
macos-latest 2.7	49s
macos-latest 3.0	41s
macos-latest 3.1	38s
macos-latest 3.2	45s
macos-latest 3.3	37s
macos-latest 3.4	44s
macos-latest head	37s
macos-latest truffleruby	59s
macos-latest truffleruby-head	1m 0s
windows-latest 2.7	6m 48s
windows-latest 3.0	5m 37s
windows-latest 3.1	4m 21s
windows-latest 3.2	3m 54s
windows-latest 3.3	4m 1s
windows-latest 3.4	8s
windows-latest head	3m 54s
windows-latest ucrt	3m 57s
windows-latest mswin	2m 28s
	1h 32m 36s

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