glibc: Avoid building and linking stub libraries that were emptied in 2.34

[alexrp]

Closes #20919.

❯ zig4 cc system.c -target x86_64-linux-gnu.2.33
❯ ldd a.out
        linux-vdso.so.1 (0x00007ffc0ba83000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x0000795644147000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x0000795643e00000)
        /lib64/ld-linux-x86-64.so.2 (0x0000795644181000)
❯ zig4 cc system.c -target x86_64-linux-gnu.2.34
❯ ldd a.out
        linux-vdso.so.1 (0x00007ffd4eb0f000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000075bec1200000)
        /lib64/ld-linux-x86-64.so.2 (0x000075bec14ba000)

See: https://sourceware.org/pipermail/libc-alpha/2021-August/129718.html (note: this includes librt too, despite it not being mentioned)

[andrewrk]

Thanks, that's a nice change.