insane: handle dangling symlinks in the libdir QA check

insane: handle dangling symlinks in the libdir QA check

The "libdir" QA check tries to open every file it finds as an ELF.  If
it finds a dangling symlink that looks like a library by the filename it
will try to open it and fail with FileNotFoundError error.  As this
dangling symlink probably points to a real file, silently absorb the
error.

[ YOCTO #13949 ]

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>