cmake: set generation of libucs on windows mingw

it is needed to provide 'factory' symbol when compiling
dynamic library of verilog-a components
Merge branch 'dynamic-loader-rebase140211' of https://github.com/guitorri/qucs into dynamic-loader-rebase140211
Merge branch 'dynamic-loader-rebase140211' of https://github.com/guitorri/qucs into dynamic-loader-rebase140211
fix name of make, mingw32-make
cleanup va2cpp, cpp2lib, dyload working Win MinGW

Dynamic loader tested with MinGW 4.8.2, Windows 8.1 (64)
Tested with CMake, autotools need fix to emit aditional
library out of ucs.cpp. A --out-implib is needed to resolve
the factory symbols defined as external on the verilog-a dll.