ProjectExplorer: Pimpl AbstractProcessStep

Change-Id: I0f77ff2e88b29674c306b394093deb2060db70c8
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/nim/project/nimcompilerbuildstepconfigwidget.cpp

@@ -31,6 +31,8 @@
 
 #include "../nimconstants.h"
 
+#include <projectexplorer/processparameters.h>
+
 #include <utils/qtcassert.h>
 
 using namespace ProjectExplorer;