Display notes from setup file in testcurl.pl

Autobuild submitters can use this to add some text to their
setup files to describe issues they've found with the build
or tests. This could include laying blame on test failures on
network issues or dependent libraries, explaining away compiler
warnings or providing any additional information that could be
useful to people reviewing and investigating problems with the
publicly available autobuild logs.  Note that persistent test
failures that are not issues with curl itself should normally be
fixed by excluding them from the test run instead.

This is an entirely optional field that is not entered by the
user the first time a new build is created.