windows/unpack: fix the version-to-number function

It used a plus ('+') instead of multiplication ('*') which made 8.11.0_4
sort above 8.11.1_0 ...

Closes #413

windows/unpack.pl

@@ -12,7 +12,7 @@
 sub num {
     my ($t)=@_;
     if($t =~ /.*(\d)\.(\d+)\.(\d+)_(\d+)/) {
-        return 1000000*$1 + 10000*$2 + 100+$3 + $4;
+        return 1000000*$1 + 10000*$2 + 100*$3 + $4;
     }
     return 0;
 }