This configure option causes the installed commands to have
a suffix string that makes them distinct from other versions
that also have a suffix string. This allows for multiple
installed versions of Icarus Verilog.
Also, move installed C/C++ header files into a subdirectory of
their own under the target include directory, to make clearer
the purpose and source of those files.
The va_math.vpi module implements systen-function versions of the
Verilog-A math functions. This library was contributed by Cary R.
Also add the constants.vams include file. This is pretty much
direct from the Verilog-AMS LRM.