Log Message:
Pre-set the value of the configure test glib_cv_rtldglobal_broken to
avoid running the test. The test, which calls dlopen("libpthread.so"),
fails on NetBSD for reasons unrelated to what it is trying to detect,
glib concludes that RTLD_GLOBAL is broken, and gmodule doesn't work.

This method of fooling configure suggested by Ron Roskens on tech-pkg.

Addresses PR pkg/20050 ("galeon fails to load at run-time").