setup.py: add export_symbols to fix compile of ctypes

Author: naveen521kk

setup.py

@@ -1433,6 +1433,10 @@ def detect_ctypes(self):
                         extra_compile_args=extra_compile_args,
                         extra_link_args=extra_link_args,
                         libraries=(['ole32', 'oleaut32', 'uuid'] if MS_WINDOWS else []),
+                        export_symbols=(
+                            ['DllGetClassObject PRIVATE', 'DllCanUnloadNow PRIVATE']
+                            if MS_WINDOWS else None
+                        ),
                         sources=sources)
         self.add(ext)
         # function my_sqrt() needs libm for sqrt()