NetBSD doesn't put packages in /usr/local like /CMakeLists.txt thought.
The `#ifdef __NetBSD__` around iconv was actually breaking compilation
on NetBSD when using the system libiconv (there's also a GNU iconv
package)
A C program included from C++ source broke on NetBSD specifically, work
around it.
This doesn't fix compilation on NetBSD, which is currently broken, but
is closer to correct.