AppImage: Copy libusb binary into image

pkg2appimage excludes libusb-1.0.so by default for no good reason:

83483c2971/excludelist (L112)

This can cause an issue when the AppImage loads the systems libusb but the
systems libusb in turn loads libudev from the AppImage. The kernel ABI for
libusb will not be changing so it is safe to bundle it into the AppImage.

-----

taken from Electron-Cash/Electron-Cash@25d45fdcbfa335d83de876ff16e978a058d17e22

contrib/build-linux/appimage/build.sh

@@ -150,6 +150,10 @@ info "finalizing AppDir."
     mv usr/include.tmp usr/include
 )
 
+# copy libusb here because it is on the AppImage excludelist and it can cause problems if we use system libusb
+info "Copying libusb"
+cp -f /usr/lib/x86_64-linux-gnu/libusb-1.0.so "$APPDIR/usr/lib/libusb-1.0.so" || fail "Could not copy libusb"
+
 
 info "stripping binaries from debug symbols."
 # "-R .note.gnu.build-id" also strips the build id