Fix compilation with mingw

On mingw, "IntType data_ = 0" fails to compile.  Update to use
IntType() instead.

Change-Id: I706c15ddb993091aeb922ba7d9ef8cc4cc23bd64
diff --git a/src/base/bit_stream.h b/src/base/bit_stream.h
index c878197..2cda093 100644
--- a/src/base/bit_stream.h
+++ b/src/base/bit_stream.h
@@ -56,7 +56,7 @@
       data_size_ -= count;
       return true;
     } else {
-      *result = 0;
+      *result = ResultType();
       return false;
     }
   }
@@ -67,7 +67,7 @@
                                          : (IntType(1) << bits) - 1;
   }
 
-  IntType data_ = 0;
+  IntType data_ = IntType();
   uint32_t data_size_ = 0;
 };