Add back undefining _POSIX_C_SOURCE and _XOPEN_SOURCE (#106)

- only undefining _POSIX_THREADS had be a problem
- see #103

Author: mrbean-bremen

src/PythonQtPythonInclude.h

@@ -33,6 +33,15 @@
 #ifndef __PythonQtPythonInclude_h
 #define __PythonQtPythonInclude_h
 
+// Undefine macros that features.h defines to avoid redefinition warning
+#ifdef _POSIX_C_SOURCE
+#  undef _POSIX_C_SOURCE
+#endif
+
+#ifdef _XOPEN_SOURCE
+#  undef _XOPEN_SOURCE
+#endif
+
 // Undefine Qt keywords that conflict with Python headers
 #ifdef slots
 #undef slots