plugins directory fails to build when enabling memory sanitizing

[WardF]

Plugins fails with 'undefined symbols' error, on OSX, when passing CFLAGS="-fsanitize=address -fno-omit-frame-pointer" to configure. I believe the issue is the -no-undefined at the top of plugins/Makefile.am. Removing this solves the issue, I need to determine why we have this ld flag added and if there is a downside to removing it. Thoughts @DennisHeimbigner ?

[DennisHeimbigner]

I think the no-undefined is related to the creation of shared libraries.
If memory serves, some systems cannot create shared libraries if there
are undefined symbols. This might be a cygwin issue.

[WardF]

I'll see if I can confirm.

[WardF]

I've confirmed this is correct. Working to add a conditional on Cygwin so that --no-undefined is added only if we're working in cygwin.

[WardF]

I see we actually check for that already in configure.ac; modifying plugins/Makefile.am to take advantage of this.

[WardF]

I've gotten it working and am waiting for travis-ci.org to finish. It is running slower now that it is a bit throttled. We'll be converting to GitHub actions soon.