Removed $(top_builddir)/include from include path

There are no configure generated files in $(top_builddir)/include.
CoordAPI: Reset NS socket on restart.

To allow it to be recreated as needed during restart.
Added test/realpath.c file.
Moved [src->include]/dlsym_default.h
For: gdb --args dmtcp_launch a.out;(gdb) r;^C;cont
Remove dmtcp_dlopen_enabled() ; not used
Apache-plugin: move to contrib directory

Also added the copyright notices.
Allow ELF GNU hash; Integrate dlsym_default w/ DMTCP
NEXT_FNC_DEFAULT(realpath), fix matlab-2012, later
Minor polishing
Add realpath test; realpath is versioned symbol
Minor polishing.