More PORTABLE fixes

Author: peterdettman

crypto/src/crypto/generators/OpenBsdBCrypt.cs

@@ -174,7 +174,11 @@ public static bool CheckPassword(string bcryptString, char[] password)
             }
             catch (Exception nfe)
             {
+#if PORTABLE
+                throw new ArgumentException("Invalid cost factor: " + bcryptString.Substring(4, 2), "bcryptString");
+#else
                 throw new ArgumentException("Invalid cost factor: " + bcryptString.Substring(4, 2), "bcryptString", nfe);
+#endif
             }
             if (cost < 4 || cost > 31)
                 throw new ArgumentException("Invalid cost factor: " + cost + ", 4 < cost < 31 expected.");

crypto/src/crypto/prng/ThreadedSeedGenerator.cs

@@ -113,7 +113,7 @@ private byte[] DoGenerateSeed(
                 finally
                 {
 #if PORTABLE
-                    autoResetEvent.Close();
+                    autoResetEvent.Dispose();
 #endif
                 }