HADOOP-14992. Upgrade Avro patch version. Contributed by Bharat Viswanadham

(cherry picked from commit e4878a59b3a380e323bb4627a69266bbf2524b36)
(cherry picked from commit 85be67ebe46b0d14e2689fecf4d56374c3a084be)

hadoop-project/pom.xml

@@ -66,7 +66,7 @@
     <java.security.egd>file:///dev/urandom</java.security.egd>
 
     <!-- avro version -->
-    <avro.version>1.7.4</avro.version>
+    <avro.version>1.7.7</avro.version>
 
     <!-- jersey version -->
     <jersey.version>1.9</jersey.version>