cipher: make output buffer String independent #1265

Job	Run time
openssl-1.0.2u	26s
openssl-1.1.0l	1m 8s
openssl-1.1.1w	26s
openssl-3.0.15	26s
openssl-3.1.7	1m 1s
openssl-3.2.3	28s
openssl-3.3.2	33s
openssl-3.4.0	30s
openssl-master	3m 54s
libressl-3.1.5	28s
libressl-3.2.7	24s
libressl-3.3.6	24s
libressl-3.4.3	31s
libressl-3.5.3	25s
libressl-3.6.3	24s
libressl-3.7.3	44s
libressl-3.8.4	25s
libressl-3.9.2	24s
libressl-4.0.0	39s
openssl-3.0.15 with fips provider	33s
openssl-3.1.7 with fips provider	28s
openssl-3.2.3 with fips provider	36s
openssl-3.3.2 with fips provider	28s
openssl-3.4.0 with fips provider	29s
openssl-master with fips provider	3m 47s
openssl-3.4.0 without legacy provider	34s
ruby-versions / Generate Ruby versions	11s
ubuntu-22.04 2.7	1m 9s
ubuntu-22.04 3.0	28s
ubuntu-22.04 3.1	34s
ubuntu-22.04 3.2	28s
ubuntu-22.04 3.3	25s
ubuntu-22.04 head	29s
ubuntu-22.04 truffleruby	1m 50s
ubuntu-22.04 truffleruby-head	1m 51s
ubuntu-20.04 2.7	1m 0s
ubuntu-20.04 3.0	26s
ubuntu-20.04 3.1	35s
ubuntu-20.04 3.2	25s
ubuntu-20.04 3.3	28s
ubuntu-20.04 head	27s
ubuntu-20.04 truffleruby	1m 35s
ubuntu-20.04 truffleruby-head	1m 41s
macos-latest 2.7	56s
macos-latest 3.0	20s
macos-latest 3.1	23s
macos-latest 3.2	33s
macos-latest 3.3	28s
macos-latest head	19s
macos-latest truffleruby	59s
macos-latest truffleruby-head	1m 7s
windows-latest 2.7	5m 44s
windows-latest 3.0	4m 16s
windows-latest 3.1	4m 17s
windows-latest 3.2	5m 45s
windows-latest 3.3	5m 21s
windows-latest head	5m 5s
windows-latest ucrt	4m 6s
windows-latest mswin	4m 7s
	1h 18m 23s

Provide feedback