make bn shareable when frozen #1224

Job	Run time
openssl-1.0.2u	53s
openssl-1.1.0l	53s
openssl-1.1.1w	1m 4s
openssl-3.0.15	59s
openssl-3.1.7	1m 4s
openssl-3.2.3	1m 1s
openssl-3.3.2	1m 0s
openssl-3.4.0	1m 0s
openssl-master	3m 42s
libressl-3.1.5	57s
libressl-3.2.7	1m 2s
libressl-3.3.6	1m 1s
libressl-3.4.3	1m 5s
libressl-3.5.3	1m 0s
libressl-3.6.3	1m 4s
libressl-3.7.3	1m 0s
libressl-3.8.4	59s
libressl-3.9.2	1m 2s
libressl-4.0.0	1m 3s
openssl-3.0.15 with fips provider	42s
openssl-3.1.7 with fips provider	42s
openssl-3.2.3 with fips provider	42s
openssl-3.3.2 with fips provider	43s
openssl-3.4.0 with fips provider	46s
openssl-master with fips provider	3m 20s
openssl-3.4.0 without legacy provider	1m 0s
ruby-versions / Generate Ruby versions	4s
ubuntu-22.04 2.7	1m 3s
ubuntu-22.04 3.0	56s
ubuntu-22.04 3.1	1m 4s
ubuntu-22.04 3.2	1m 4s
ubuntu-22.04 3.3	1m 1s
ubuntu-22.04 head	1m 1s
ubuntu-22.04 truffleruby	1m 38s
ubuntu-22.04 truffleruby-head	1m 52s
ubuntu-20.04 2.7	1m 4s
ubuntu-20.04 3.0	1m 2s
ubuntu-20.04 3.1	1m 3s
ubuntu-20.04 3.2	1m 5s
ubuntu-20.04 3.3	1m 1s
ubuntu-20.04 head	59s
ubuntu-20.04 truffleruby	1m 36s
ubuntu-20.04 truffleruby-head	1m 47s
macos-latest 2.7	51s
macos-latest 3.0	48s
macos-latest 3.1	42s
macos-latest 3.2	42s
macos-latest 3.3	52s
macos-latest head	1m 3s
macos-latest truffleruby	1m 3s
macos-latest truffleruby-head	1m 10s
windows-latest 2.7	6m 2s
windows-latest 3.0	4m 17s
windows-latest 3.1	4m 30s
windows-latest 3.2	5m 39s
windows-latest 3.3	4m 29s
windows-latest head	4m 12s
windows-latest ucrt	4m 0s
windows-latest mswin	2m 51s
	1h 32m 15s

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