nsis: simplify

extras/package/win32/NSIS/vlc.win32.nsi.in

@@ -428,11 +428,10 @@ Function .onInit
 ${MementoSectionRestore}
 
 @HAVE_WIN64_TRUE@ !include "x64.nsh"
-@HAVE_WIN64_TRUE@ ${If} ${RunningX64}
-@HAVE_WIN64_TRUE@ ${Else}
+@HAVE_WIN64_TRUE@ ${Unless} ${RunningX64}
 @HAVE_WIN64_TRUE@    MessageBox MB_OK|MB_ICONSTOP "This version of VLC only runs on 64bits operating systems.$\nYour operating system is 32bits.$\n$\nPlease get the 32 BITS version."
 @HAVE_WIN64_TRUE@    Quit
-@HAVE_WIN64_TRUE@ ${Endif}
+@HAVE_WIN64_TRUE@ ${EndUnless}
 ${If} ${AtLeastWinXP}
     ${If} ${IsWinXP}
     ${AndIf} ${AtMostServicePack} 1