rar: import unrarsrc-5.5.8 for reference

this will allow us to diff against newer version of unrarsrc if we wish to update our port

reference/unrar/smallfn.cpp

@@ -0,0 +1,19 @@
+#include "rar.hpp"
+
+int ToPercent(int64 N1,int64 N2)
+{
+  if (N2<N1)
+    return 100;
+  return ToPercentUnlim(N1,N2);
+}
+
+
+// Allows the percent larger than 100.
+int ToPercentUnlim(int64 N1,int64 N2)
+{
+  if (N2==0)
+    return 0;
+  return (int)(N1*100/N2);
+}
+
+