Remove obsolete NSIS build

distribution/windows/build.ps1

@@ -1,11 +0,0 @@
-param (
-    [Parameter(Position = 1)]
-    [string]$VersionExtra = ""
-)
-
-$path = Split-Path $Script:MyInvocation.MyCommand.Path
-Write-Host "Building Windows Installer (NSIS script)";
-Write-Host "  $VersionExtra";
-makensis   /DAPPV_EXTRA=$VersionExtra         `
-           /DVERSION_INCLUDE=$path\win32.txt  `
-         $path\install.nsi > $path\win32.log;