* added makefile goals of 'static' and 'dynamic'
* chenged goal 'all' to build both static and dynamic in preparation for 'make install'
* added logic to detect GNU's ld version 2.15 or later
* added recipe to include -z relro and -z now if LD215_OR_LATER==1
* modified 'install' to continue on a copy error
* modified 'clean' to continue on error
Tested on OpenBSD 4.9, FreeBSD 8.2, Fedora 14 & 15, Ubuntu 10 & 11.