Deframer.deframe returns number of unprocessed bytes.

This is intended to reduce the flakiness of test_TestServiceBenchmarks.
TAP showed some flaky runs where HttpStreamDeframer threw the exception
"GRPC stream not correctly aligned".

-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=69166650

core/src/main/java/com/google/net/stubby/transport/InputStreamDeframer.java

@@ -22,15 +22,17 @@ public class InputStreamDeframer extends Deframer<InputStream> {
 
   /**
    * Deframing a single input stream that contains multiple GRPC frames
+   *
+   * @return the number of unconsumed bytes remaining in the buffer
    */
   @Override
   public int deframe(InputStream frame, Operation target) {
     try {
-      int read = 0;
-      while (frame.available() > 0) {
-        read += super.deframe(frame, target);
-      }
-      return read;
+      int remaining;
+      do {
+        remaining = super.deframe(frame, target);
+      } while (frame.available() > 0);
+      return remaining;
     } catch (IOException ioe) {
       throw new RuntimeException(ioe);
     }