Freestyle: Fix for VC++ warnings about 'hypot' macro redefinitions (Part 2).

(See commit e1771e72fbbf828dbf5bed871b814288389f3611 for more detail of
the problem).

Fixed for #include <Python.h> not properly put in the extern "C" { ... } construct.

Also removed redundant inclusion of the header file in the Freestyle Python API code.

source/blender/freestyle/intern/python/BPy_ViewMap.h

@@ -25,7 +25,9 @@
 #ifndef __FREESTYLE_PYTHON_VIEWMAP_H__
 #define __FREESTYLE_PYTHON_VIEWMAP_H__
 
+extern "C" {
 #include <Python.h>
+}
 
 #include "../view_map/ViewMap.h"