gmacros: Do not redefine NULL on C++
Even though having NULL as nullptr should be the standard for newer C++ versions, it may break some headers, so let's not touch it for now.
Closes: #2973 (closed)
Even though having NULL as nullptr should be the standard for newer C++ versions, it may break some headers, so let's not touch it for now.
Closes: #2973 (closed)