library-cmp: Handle filters for the fully-qualified symbols name

If a filter pattern has an '@' in it, it's safe to assume that it is
expected to be compared against the `symbol@version` fully-qualified
name.
Instead if there isn't an '@', like before, we just compare it against
only the symbol.

Signed-off-by: Ludovico de Nittis <ludovico.denittis@collabora.com>
7 jobs for support_newer_glibc in 10 minutes and 30 seconds (queued for 9 seconds)
Status Name Job ID Coverage
  Test
manual build:arch #109453
allowed to fail manual
passed build:asan #109449

00:05:04

passed build:bionic #109452

00:10:29

passed build:buster #109451

00:09:01

passed build:stretch #109450

00:10:13

passed build:ubsan #109448

00:03:58

passed reuse #109454

00:03:26