+AC_ARG_ENABLE(canonical-system-headers,
+[ --enable-canonical-system-headers
+ enable or disable system headers canonicalization],
+[],
+enable_canonical_system_headers=yes)
+if test $enable_canonical_system_headers != no; then
+ AC_DEFINE(ENABLE_CANONICAL_SYSTEM_HEADERS,
+ 1, [Define to enable system headers canonicalization.])
+fi
+