complex configure tests involving multiple files and possibly libtool/automake

[Václav Haisman]

Hi.

I have a test that I would like to run during configure time which
basically involves compiling two files and linking a shared object/DLL
out of them. I think I would like to be using automake/libtool to
compile and link the configure test itself. Is there a good practice
or good example on how to do this?

Before you comment, no, simple single file compile and link will not
do. This is in attempt to detect issue on Cygwin with C++11
`thread_local`. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64697#.

-- 
VH