[PATCH v3] elf: Restore ldconfig libc6 implicit soname logic [BZ #30125]

[Florian Weimer]

* Joan Bruguera via Libc-alpha:

> +$CC /dev/null -o $testroot/lib/libsomething.so.1.2.3 -shared

This links against the system libc and not the libc under test.

I'd suggest to build another module in elf/Makefile, have
$(objpfx)tst-ldconfig-no-soname.out depend on it.  This way, it will be
built before the test script runs.

Thanks,
Florian