Fixup lint flags.

The -build/include setting was masking out build/include_what_you_use. This CL
restores them, fixes any build errors, and adds NOLINT as needed. As well,
the runtime/explicit and runtime/printf flags are aslo enabled and NOLINT'd.
lint cleanups

Change-Id: Ib013b3eb29c8d0e48cad74c5df9028684130719f
Reviewed-on: https://pdfium-review.googlesource.com/2030
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/core/fxcrt/fx_ext.h b/core/fxcrt/fx_ext.h
index b7fd6f6..7d8529e 100644
--- a/core/fxcrt/fx_ext.h
+++ b/core/fxcrt/fx_ext.h
@@ -9,6 +9,7 @@
 
 #include <cctype>
 #include <cwctype>
+#include <memory>
 
 #include "core/fxcrt/fx_basic.h"