Gets builds working on Windows (VS 2015) (#37)

Def files will be updated after the latest PR with new definitions gets
added.

src/UsbUtil.cpp

@@ -23,6 +23,8 @@
 
 namespace cs {
 
+#ifdef __linux__
+
 static llvm::StringRef GetUsbNameFromFile(int vendor, int product,
                                           llvm::SmallVectorImpl<char>& buf) {
   int fd = open("/var/lib/usbutils/usb.ids", O_RDONLY);
@@ -110,8 +112,6 @@ llvm::StringRef GetUsbNameFromId(int vendor, int product,
   return os.str();
 }
 
-#ifdef __linux__
-
 int CheckedIoctl(int fd, unsigned long req, void* data, const char* name,
                  const char* file, int line, bool quiet) {
   int retval = ioctl(fd, req, data);