Apply Chromium style fixes.

This addresses several minor code quality issues that are validated
in Chromium, but not yet applied to ANGLE:

* constructors and destructors must be defined out-of-line
* auto is not allowed for simple pointer types
* use override everywhere instead of virtual
* virtual functions must also be defined out-of-line

Slightly reduces binary size for me (~2k on Win, 150k on Linux).

Bug: angleproject:1569
Change-Id: I073ca3365188caf5f29fb28d9eb207903c1843e6
Reviewed-on: https://chromium-review.googlesource.com/779959
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/preprocessor/Macro.h b/src/compiler/preprocessor/Macro.h
index f835c42..c42e172 100644
--- a/src/compiler/preprocessor/Macro.h
+++ b/src/compiler/preprocessor/Macro.h
@@ -27,7 +27,8 @@
     typedef std::vector<std::string> Parameters;
     typedef std::vector<Token> Replacements;
 
-    Macro() : predefined(false), disabled(false), expansionCount(0), type(kTypeObj) {}
+    Macro();
+    ~Macro();
     bool equals(const Macro &other) const;
 
     bool predefined;