Use override in all the places where it is possible

This will avoid -Winconsistent-overrides in the future. Done using the
-Wsuggest-override warning of GCC 5.1

BUG=

Change-Id: I707a649dc368f5dd1e139fd144370abcac0b6263
Reviewed-on: https://chromium-review.googlesource.com/294920
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/compiler/translator/InitializeVariables.h b/src/compiler/translator/InitializeVariables.h
index 44f377a..2a141ec 100644
--- a/src/compiler/translator/InitializeVariables.h
+++ b/src/compiler/translator/InitializeVariables.h
@@ -33,13 +33,13 @@
     }
 
   protected:
-    virtual bool visitBinary(Visit, TIntermBinary *node) { return false; }
-    virtual bool visitUnary(Visit, TIntermUnary *node) { return false; }
-    virtual bool visitSelection(Visit, TIntermSelection *node) { return false; }
-    virtual bool visitLoop(Visit, TIntermLoop *node) { return false; }
-    virtual bool visitBranch(Visit, TIntermBranch *node) { return false; }
+    bool visitBinary(Visit, TIntermBinary *node) override { return false; }
+    bool visitUnary(Visit, TIntermUnary *node) override { return false; }
+    bool visitSelection(Visit, TIntermSelection *node) override { return false; }
+    bool visitLoop(Visit, TIntermLoop *node) override { return false; }
+    bool visitBranch(Visit, TIntermBranch *node) override { return false; }
 
-    virtual bool visitAggregate(Visit visit, TIntermAggregate* node);
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
 
   private:
     void insertInitCode(TIntermSequence *sequence);