Change license to LPGLv2+

We relax the license so that the software can be used by more
projects. - wk (g10 Code CEO)

The software was written by g10 Code employees or contractors
with two minor external patches:

commit a49a061c65fb3a6d9c58add4dc55435f0c4353a2
Author: Jim Meyering <meyering@fb.com>
AuthorDate: Fri Jun 5 08:03:00 2015 -0700

configure.ac: improve check for clock_gettime library

• configure.ac: When using AC_SEARCH_LIBS, handle the case in which that function returns "none required". Also, save and restore LIBS around the check, and properly m4-quote the first argument to AC_DEFINE. Finally, also set and AC_SUBST LIB_CLOCK_GETTIME. This added code is very similar to that provided in gnulib's clock-time.m4.
• tests/Makefile.am (LDADD): Append $(LIB_CLOCK_GETTIME).

and

commit 95754492a41c8284264476f05e3fe3c50c3b4aa9
Author: Ben Kibbey <bjk@luxsci.net>
AuthorDate: Mon Nov 19 23:04:07 2012 -0500

Build fix for NetBSD.

• src/npth.c (npth_setname_np): conditional check for NetBSD and adapt correct parameters.