* dlfcn/Makefile (distribute): Add glreflib1.c and glreflib2.c.
(tests): Add glrefmain.
Add rules to build modules and run tests. Ignore result of glrefmain
for now since it fails.
* dlfcn/glrefmain.c: New file.
* dlfcn/glreflib1.c: New file.
* dlfcn/glreflib2.c: New file.
* test-skeleton.c: Include <string.h> for strsignal prototype.
