Change order of includes for Ubuntu

Author: mdboom

src/_png.cpp

@@ -10,30 +10,22 @@
    of harmless warnings.
 */
 
-#include <vector>
 
 #include "numpy_cpp.h"
 #include "mplutils.h"
 #include "file_compat.h"
 
 extern "C" {
-#ifdef __linux__
 #   include <png.h>
 #   ifdef _POSIX_C_SOURCE
 #       undef _POSIX_C_SOURCE
 #   endif
 #   ifdef _XOPEN_SOURCE
 #       undef _XOPEN_SOURCE
 #   endif
-#   include "Python.h"
-#else
-
-/* Python API mandates Python.h is included *first* */
-#   include "Python.h"
-
-#   include <png.h>
-#endif
 }
+#   include <vector>
+#   include "Python.h"
 
 
 // As reported in [3082058] build _png.so on aix