Update to go1.21rc3
    
    Update bundled dependencies.
    Update pcre-devel to pcre2-devel
    Add go-filesystem
    Remove skipping tests, related: https://github.com/golang/go/issues/39466
    Remove 0002-syscall-expose-IfInfomsg.X__ifi_pad-on-s390x.patch, already merged
    Rename 0003-cmd-go-disable-Google-s-proxy-and-sumdb.patch to 0001-Disable-Google-s-proxy-sumdb-and-toolchain.patch
    Update 0001-Disable-Google-s-proxy-sumdb-and-toolchain.patch
    Update 0004-cmd-link-use-gold-on-ARM-ARM64-only-if-gold-is-avail.patch
    
    Resolves: rhbz#2128303
    Resolves: rhbz#2215635
    Resolves: rhbz#2172392