Makefile fix/enhancement.
Makefile fix/enhancement.

 * Fixed incorrect version string in library.

 * Compiles with -O2 rather than no optimization.

 * Added 'debug' target.  This may not work for non-GNU makes.

Signed-off-by: David Favro <b8bd907ab8ef6373a93fcf7bd4a558577fadb869@meta-dynamic.com>

luaposix/luaposix,jimmyharris/luaposix,jimmyharris/luaposix,rrthomas/luaposix,ardje/luaposix,zevv/luaposix,zevv/luaposix,snegovick/luaposix,snegovick/luaposix,ardje/luaposix,rrthomas/luaposix