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/translator/Cache.cpp b/src/compiler/translator/Cache.cpp
index 07cc5b2..417e824 100644
--- a/src/compiler/translator/Cache.cpp
+++ b/src/compiler/translator/Cache.cpp
@@ -57,6 +57,10 @@
 
 TCache *TCache::sCache = nullptr;
 
+TCache::TCache()
+{
+}
+
 void TCache::initialize()
 {
     if (sCache == nullptr)