Convert some 0 to nullptr

Change-Id: Ib3ca8e2cc0d63fd35582c73b3cf7c915fb64ddfb
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/projectexplorer/processparameters.cpp

@@ -47,7 +47,7 @@
 using namespace ProjectExplorer;
 
 ProcessParameters::ProcessParameters() :
-    m_macroExpander(0),
+    m_macroExpander(nullptr),
     m_commandMissing(false)
 {
 }