Figure out why on Ubuntu a system-wide openssl is used

[thresheek]

As evidenced by github actions warnings

[oxpa]

Because we download prebuilt binaries for unitctl and those are built with system wide openssl:

:/home/linuxbrew/.linuxbrew/Homebrew/Library/Taps/nginx/homebrew-unit# ldd /home/linuxbrew/.linuxbrew/Cellar/unit/1.33.0/bin/unit{d,ctl} | grep -E '^/|ssl'
/home/linuxbrew/.linuxbrew/Cellar/unit/1.33.0/bin/unitd:
        libssl.so.3 => /home/linuxbrew/.linuxbrew/opt/openssl@3/lib/libssl.so.3 (0x00007d46e3b72000)
        libcrypto.so.3 => /home/linuxbrew/.linuxbrew/opt/openssl@3/lib/libcrypto.so.3 (0x00007d46e361c000)
/home/linuxbrew/.linuxbrew/Cellar/unit/1.33.0/bin/unitctl:
        libssl.so.3 => /lib/x86_64-linux-gnu/libssl.so.3 (0x00007b8e1277e000)

[thresheek]

huh, not very portable then