Patch from Lorenzo M. Catucci:

akuchling · akuchling · commit ea34a84e543e · 2000-06-18T19:06:49.000Z
I discovered the [MREMAP_MAYMOVE] symbol is only defined when _GNU_SOURCE is
defined; therefore, here is the change: if we are compiling for linux,
define _GNU_SOURCE before including mman.h, and all is done.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
@@ -16,6 +16,11 @@
  / ftp://squirl.nightmare.com/pub/python/python-ext.
 */
 
+#ifdef __linux__
+#define _GNU_SOURCE  /* So we can get MREMAP_MAYMOVE defined when
+		        sys/mman.h is included */
+#endif
+
 #include <Python.h>
 
 #ifndef MS_WIN32
