cmake: Explicitly link libusb at runtime for version check in Windows

FindLibUSB.cmake presents issues with its try_compile() invocation
when using some dated CMake versions, such as 2.8.7 and 2.8.11, while
operating fine with more recent versions (e.g., 2.8.12.2, 3.0.0).

Using try_run() is a cleaner solution than a combination of try_compile() and
execute_process(). However, in Windows we need to stage libusb-1.0.dll in the
directory containing the resulting libusb_version.exe. As try_run() creates a
a temporary build directory and deletes it when done, this originally
posed a challenge to copying libusb-1.0.dll to the correct directory.

To address both of these challenges, the Windows version of this program now
explicitly links libusb at runtime, provided the path to the libusb DLL.

OSX and Linux variants assume libusb is in the library path, and link against
the library at compile-time.