Fem: [skip ci] fix compiler warnings

* add Python.h to PreCompiled.h to fix warning for MSVC: warning C4005: 'COMPILER': macro redefinition
* add Python.h to FemPostPipelinePyImp.cpp to fix warning for clang: pyconfig.h:1672:9: warning: '_LARGEFILE_SOURCE' macro redefined [-Wmacro-redefined]

src/Mod/Fem/App/FemPostPipelinePyImp.cpp

@@ -22,6 +22,9 @@
 
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+#include <Python.h>
+#endif
 
 #include "FemPostPipeline.h"
 #include <Base/FileInfo.h>

src/Mod/Fem/App/PreCompiled.h

@@ -54,6 +54,8 @@
 #include <boost/assign/list_of.hpp>
 #include <boost/tokenizer.hpp>
 
+#include <Python.h>
+
 // Salomesh
 #include <SMESH_Version.h>
 #include <SMESH_Gen.hxx>