win32: Avoid exporting non-public symbols with declspec dllexport
win32: Avoid exporting non-public symbols with declspec dllexport

fishjam/libusbmuxd,wangwei1237/libusbmuxd,libimobiledevice-win32/libusbmuxd,libimobiledevice/libusbmuxd,aburgh/libusbmuxd,fishjam/libusbmuxd,wangwei1237/libusbmuxd,libimobiledevice/libusbmuxd,libimobiledevice-win32/libusbmuxd,aburgh/libusbmuxd