Patch #1464444: Add --with-system-ffi.
diff --git a/README b/README
index beaefca..26e0ec0 100644
--- a/README
+++ b/README
@@ -1068,6 +1068,9 @@
 
 --with-tsc: Profile using the Pentium timestamping counter (TSC).
 
+--with-system-ffi:  Build the _ctypes extension module using an ffi
+	library installed on the system.
+
 
 Building for multiple architectures (using the VPATH feature)
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