openssl: Also bootstrap CA bundle using System keychain
openssl: Also bootstrap CA bundle using System keychain

Add /Library/Keychains/System.keychain to the keychains used for
for seeding the cert.pem bundle.

System.keychain is the authorative keychain for organization
installed CAs.

SystemRootCertificates.keychain is only for default Apple installed
CAs.

Fixes: https://github.com/Homebrew/homebrew-core/issues/5291

Closes #71191.

Co-authored-by: Mike McQuaid <a17fed27eaa842282862ff7c1b9c8395a26ac320@mikemcquaid.com>
Signed-off-by: Sean Molenaar <2b250e3fea88cfef248b497ad5fc17f7dc435154@users.noreply.github.com>

sjackman/homebrew-core,adam-moss/homebrew-core,nandub/homebrew-core,chrisfinazzo/homebrew-core,makigumo/homebrew-core,Homebrew/homebrew-core,mbcoguno/homebrew-core,makigumo/homebrew-core,lemzwerg/homebrew-core,stgraber/homebrew-core,Linuxbrew/homebrew-core,lemzwerg/homebrew-core,chrisfinazzo/homebrew-core,mbcoguno/homebrew-core,JCount/homebrew-core,mfikes/homebrew-core,nbari/homebrew-core,filcab/homebrew-core,filcab/homebrew-core,mbcoguno/homebrew-core,Homebrew/homebrew-core,uyjulian/homebrew-core,nbari/homebrew-core,nandub/homebrew-core,Moisan/homebrew-core,cblecker/homebrew-core,cblecker/homebrew-core,adam-moss/homebrew-core,zyedidia/homebrew-core,uyjulian/homebrew-core,Moisan/homebrew-core,JCount/homebrew-core,zyedidia/homebrew-core,sjackman/homebrew-core,mfikes/homebrew-core,stgraber/homebrew-core,Linuxbrew/homebrew-core