buildroot/package/ed/ed-configure-CPP.patch

this old configure script has broken CPP logic is CPP is set in the
host environment

--- ed-0.2/configure
+++ ed-0.2/configure
@@ -731,6 +731,8 @@
 rm -f conftest*
   ac_cv_prog_CPP="$CPP"
 fi
+else
+  ac_cv_prog_CPP="$CPP"
 fi
 CPP="$ac_cv_prog_CPP"
 echo "$ac_t""$CPP" 1>&4