Several corrections to make sure code compiles with gcc and doesn't generate warnings

Change-Id: I63e72ba724233953e9f36b11eca37070d6e06372
diff --git a/src/hash-helper.h b/src/hash-helper.h
index 41a8b8a..86b87c9 100644
--- a/src/hash-helper.h
+++ b/src/hash-helper.h
@@ -111,7 +111,7 @@
     if (m_length > otherHash.m_length)
       return false;
 
-    for (int i = 0; i < m_length; i++)
+    for (unsigned int i = 0; i < m_length; i++)
       {
         if (m_buf [i] < otherHash.m_buf [i])
           return true;