dtls: Don't abort on non-fatal issues

OpenSSL will take care of returning valid context if there are
only non-fatal issues. Don't abort in those cases and instead just
print out the issues

Fixes gstreamer/gst-plugins-bad#811
9 jobs for <span class="ref-name">dtlsissue</span> in 34 minutes and 53 seconds (queued for 32 minutes and 39 seconds)
Status Job ID Name Coverage
  Preparation
passed #114441
gst indent

00:00:30

passed #114440
manifest

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  Build
passed #114442
build fedora x86_64

00:05:08

 
  Test
passed #114620
check fedora

00:04:08

failed #114443
check fedora

00:03:45

 
  Full Builds
passed #114444
build android arm64 api28

00:03:47

passed #114446
build cerbero cross win32

00:08:38

passed #114447
build cerbero cross win64

00:05:04

passed #114445
build cerbero fedora x86_64

00:07:16