Test for empty X500Name equality

- fix legacy X509Name construction from empty string

Author: peterdettman

core/src/main/java/org/bouncycastle/asn1/x509/X509Name.java

@@ -1079,6 +1079,11 @@ public boolean equals(Object obj)
         {
             return false;
         }
+
+        if (orderingSize == 0)
+        {
+            return true;
+        }
 
         boolean[] indexes = new boolean[orderingSize];
         int       start, end, delta;

core/src/main/java/org/bouncycastle/asn1/x509/X509NameTokenizer.java

@@ -25,18 +25,18 @@ public X509NameTokenizer(
         char separator)
     {
         this.value = oid;
-        this.index = -1;
+        this.index = oid.length() < 1 ? 0 : -1;
         this.separator = separator;
     }
 
     public boolean hasMoreTokens()
     {
-        return (index != value.length());
+        return index < value.length();
     }
 
     public String nextToken()
     {
-        if (index == value.length())
+        if (index >= value.length())
         {
             return null;
         }

core/src/test/java/org/bouncycastle/asn1/test/X500NameTest.java

@@ -435,6 +435,8 @@ public void performTest()
             fail("strict comparison failed");
         }
 
+        equalityTest(new X500Name(""), new X500Name(""));
+
         //
         // inequality to sequences
         //

core/src/test/java/org/bouncycastle/asn1/test/X509NameTest.java

@@ -402,6 +402,8 @@ public void performTest()
 
         equalityTest(n1, n2);
 
+        equalityTest(new X509Name(""), new X509Name(""));
+
         //
         // inequality to sequences
         //