Default profiles do not allow to read `/etc/ld-musl-*.path`

/etc/ld-musl-x86_64.path is required to perform dynamic linking. So almost every program will fail to run without it.

An example of this file:

/usr/lib/gcc/x86_64-gentoo-linux-musl/13
/lib
/usr/lib
/usr/local/lib
/usr/lib/rust/lib
/usr/lib/llvm/16/lib

So this is completely harmless.

Audit log:

type=AVC msg=audit(1686087677.497:67): apparmor="DENIED" operation="open" class="file" profile="syslog-ng" name="/etc/ld-musl-x86_64.path" pid=25866 comm="syslog-ng" requested_mask="r" denied_mask="r" fsuid=0 ouid=0

This is a one-line addition to abstractions/base.

@{etc_ro}/ld-musl-*.path            r,

I will make a merge request.