The big NULL replacement party part 1.

This is meant to be a safer alternative since
NULL can often be 0. Let's not rely on that.

And yes, I know this is a lot of files. This is
a safer thing to do in big commits vs for loops.

src/archutils/Unix/Backtrace.cpp

@@ -119,7 +119,7 @@ static int get_readable_ranges( const void **starts, const void **ends, int size
 			/* If, for some reason, either end is NULL, skip it; that's our terminator. */
 			const void *start = (const void *) xtoi( line );
 			const void *end = (const void *) xtoi( hyphen+1 );
-			if( start != NULL && end != NULL )
+			if( start != nullptr && end != nullptr )
 			{
 				*starts++ = start;
 				*ends++ = end;