artf4107: clang-modernize was run on WPILib

Loops were converted to their range-based equivalents, variable types were replaced with auto where the type was already specified on the same line, the override keyword was added, and instances of NULL and assignments of 0 to pointers were replaced with nullptr.

Change-Id: If281e46a2e2e1c37f278d56df9915236d4b2c864

wpilibc/wpilibC++/src/Commands/WaitForChildren.cpp

@@ -23,5 +23,5 @@ void WaitForChildren::End() {}
 void WaitForChildren::Interrupted() {}
 
 bool WaitForChildren::IsFinished() {
-  return GetGroup() == NULL || GetGroup()->GetSize() == 0;
+  return GetGroup() == nullptr || GetGroup()->GetSize() == 0;
 }