CI: Check compiler warnings. #730

Job	Run time
openssl-1.0.2u	2m 52s
openssl-1.1.0l	2m 5s
openssl-1.1.1t	2m 57s
openssl-3.0.8	4m 9s
libressl-3.1.5	3m 45s
libressl-3.2.7	2m 58s
libressl-3.3.6	3m 32s
libressl-3.4.3	2m 56s
libressl-3.5.3	2m 57s
libressl-3.6.1	3m 1s
libressl-3.7.0	3m 6s
openssl-3.0.8 fips	4m 17s
ruby-versions / Generate Ruby versions	2s
ubuntu-22.04 2.6	46s
ubuntu-22.04 2.7	1m 21s
ubuntu-22.04 3.0	1m 15s
ubuntu-22.04 3.1	1m 9s
ubuntu-22.04 3.2	1m 4s
ubuntu-22.04 head	1m 13s
ubuntu-22.04 truffleruby	1m 49s
ubuntu-22.04 truffleruby-head	1m 15s
ubuntu-20.04 2.6	50s
ubuntu-20.04 2.7	1m 12s
ubuntu-20.04 3.0	1m 3s
ubuntu-20.04 3.1	1m 3s
ubuntu-20.04 3.2	1m 2s
ubuntu-20.04 head	1m 14s
ubuntu-20.04 truffleruby-head	1m 11s
macos-latest 2.6	1m 39s
macos-latest 2.7	4m 32s
macos-latest 3.0	2m 41s
macos-latest 3.1	1m 27s
macos-latest 3.2	1m 55s
macos-latest head	1m 45s
macos-latest truffleruby-head	6h 0m 14s
windows-latest 2.6	9m 56s
windows-latest 2.7	6m 39s
windows-latest 3.0	7m 46s
windows-latest 3.1	6m 55s
windows-latest 3.2	5m 11s
windows-latest ucrt	4m 28s
windows-latest mswin	3m 25s
	7h 54m 37s

Provide feedback