Win32: fix the copying of the plugins in the installer

Also, don't copy the sdk folder
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

extras/package/win32/NSIS/helpers/install.nsh

@@ -29,7 +29,7 @@
 !macroend
 
 !macro InstallFolder FOLDER
-  File /r "${FOLDER}\*.*"
+  File /r /x sdk "${FOLDER}"
   Push "${FOLDER}"
   Call InstallFolderInternal
 !macroend