Fix harmless MSVC warning in DoxygenTranslator code.

Explicitly compare pointer with NULL instead of implicitly converting it to
bool as this resulted in MSVS "warning C4800: forcing value to bool 'true' or
'false' (performance warning)".

Source/DoxygenTranslator/src/DoxygenTranslator.cpp

@@ -25,7 +25,7 @@ DoxygenTranslator::~DoxygenTranslator() {
 
 
 bool DoxygenTranslator::hasDocumentation(Node *node) {
-  return getDoxygenComment(node);
+  return getDoxygenComment(node) != NULL;
 }