Document --with-cxx.
diff --git a/README b/README
index af76173..5bde2b8 100644
--- a/README
+++ b/README
@@ -666,6 +666,15 @@
--with-libs='libs': Add 'libs' to the LIBS that the python interpreter
is linked against.
+--with-cxx=<compiler>: Some C++ compilers require that main() is
+ compiled with the C++ if there is any C++ code in the application.
+ Specifically, g++ on a.out systems may require that to support
+ construction of global objects. With this option, the main() function
+ of Python will be compiled with <compiler>; use that only if you
+ plan to use C++ extension modules, and if your compiler requires
+ compilation of main() as a C++ program.
+
+
--with-pydebug: Enable additional debugging code to help track down
memory management problems. This allows printing a list of all
live objects when the interpreter terminates.