Reduce OpenSSL::Buffering#do_write overhead #1306

Job	Run time
openssl-1.0.2u	57s
openssl-1.1.0l	58s
openssl-1.1.1w	56s
openssl-3.0.15	58s
ruby-versions / Generate Ruby versions	3s
openssl-3.1.7	56s
openssl-3.2.3	1m 4s
openssl-3.3.2	59s
openssl-3.4.0	56s
openssl-master	3m 48s
libressl-3.1.5	1m 1s
libressl-3.2.7	1m 5s
libressl-3.3.6	59s
libressl-3.4.3	58s
libressl-3.5.3	1m 2s
libressl-3.6.3	59s
libressl-3.7.3	54s
libressl-3.8.4	58s
libressl-3.9.2	55s
libressl-4.0.0	57s
openssl-3.0.15 with fips provider	49s
openssl-3.1.7 with fips provider	51s
openssl-3.2.3 with fips provider	48s
openssl-3.3.2 with fips provider	53s
openssl-3.4.0 with fips provider	51s
openssl-master with fips provider	3m 49s
openssl-3.4.0 without legacy provider	56s
ubuntu-22.04 2.7	57s
ubuntu-22.04 3.0	59s
ubuntu-22.04 3.1	57s
ubuntu-22.04 3.2	1m 2s
ubuntu-22.04 3.3	59s
ubuntu-22.04 3.4	1m 4s
ubuntu-22.04 head	59s
ubuntu-22.04 truffleruby	1m 33s
ubuntu-22.04 truffleruby-head	1m 47s
ubuntu-20.04 2.7	1m 3s
ubuntu-20.04 3.0	1m 2s
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 0s
ubuntu-20.04 head	1m 2s
ubuntu-20.04 truffleruby	1m 29s
ubuntu-20.04 truffleruby-head	1m 50s
macos-latest 2.7	1m 1s
macos-latest 3.0	41s
macos-latest 3.1	45s
macos-latest 3.2	38s
macos-latest 3.3	50s
macos-latest 3.4	39s
macos-latest head	46s
macos-latest truffleruby	58s
macos-latest truffleruby-head	1m 4s
windows-latest 2.7	4m 41s
windows-latest 3.0	4m 24s
windows-latest 3.1	4m 37s
windows-latest 3.2	4m 25s
windows-latest 3.3	5m 15s
windows-latest 3.4	5m 7s
windows-latest head	4m 9s
windows-latest ucrt	4m 16s
windows-latest mswin	3m 10s
	1h 38m 23s

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