Append flags from environment variables. #724

Job	Run time
openssl-1.0.2u	3m 38s
openssl-1.1.0l	2m 27s
openssl-1.1.1t	2m 22s
openssl-3.0.8	5m 2s
libressl-3.1.5	4m 19s
libressl-3.2.7	3m 13s
libressl-3.3.6	3m 45s
libressl-3.4.3	3m 1s
libressl-3.5.3	3m 13s
libressl-3.6.1	3m 2s
libressl-3.7.0	3m 10s
openssl-3.0.8 fips	5m 40s
ruby-versions / Generate Ruby versions	3s
ubuntu-22.04 2.6	1m 13s
ubuntu-22.04 2.7	1m 9s
ubuntu-22.04 3.0	1m 17s
ubuntu-22.04 3.1	1m 20s
ubuntu-22.04 3.2	1m 32s
ubuntu-22.04 head	1m 17s
ubuntu-22.04 truffleruby	1m 42s
ubuntu-22.04 truffleruby-head	1m 49s
ubuntu-20.04 2.6	1m 13s
ubuntu-20.04 2.7	1m 26s
ubuntu-20.04 3.0	1m 25s
ubuntu-20.04 3.1	1m 7s
ubuntu-20.04 3.2	1m 7s
ubuntu-20.04 head	59s
ubuntu-20.04 truffleruby-head	1m 56s
macos-latest 2.6	2m 6s
macos-latest 2.7	2m 3s
macos-latest 3.0	1m 20s
macos-latest 3.1	1m 23s
macos-latest 3.2	1m 43s
macos-latest head	1m 24s
macos-latest truffleruby-head	3m 37s
windows-latest 2.6	7m 11s
windows-latest 2.7	6m 19s
windows-latest 3.0	6m 28s
windows-latest 3.1	7m 19s
windows-latest 3.2	5m 19s
windows-latest ucrt	4m 40s
windows-latest mswin	2m 34s
	1h 56m 53s

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