The Hamlib specific dependencies on Windows platforms are:
- libwinpthread-1.dll 
for both x86 and x64,
and also
- libgcc_s_sjlj-1.dll for x86 targets only. 

Those dependencies are installed from external/msvc/[x86|x64] dirs.

In addition, Hamlib also uses libusb but since it is a common
dependency with SoapySDR, it is not included in the external dirs.