Refactoring: replace NULL by nullptr for pointers (2nd CL).

This CL mainly handles the pointer comparisons (== or !=).

BUG=angleproject:2001

Change-Id: I25ac3b61032e7ad91459a1c6541cadc87cf9b160
Reviewed-on: https://chromium-review.googlesource.com/483935
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/SymbolTable.h b/src/compiler/translator/SymbolTable.h
index c348943..e76768f 100644
--- a/src/compiler/translator/SymbolTable.h
+++ b/src/compiler/translator/SymbolTable.h
@@ -431,8 +431,8 @@
 
     TSymbol *find(const TString &name,
                   int shaderVersion,
-                  bool *builtIn   = NULL,
-                  bool *sameScope = NULL) const;
+                  bool *builtIn   = nullptr,
+                  bool *sameScope = nullptr) const;
 
     TSymbol *findGlobal(const TString &name) const;