Avoid linking with zlib, which is a dependency of openssl, not ours.
Index: stunnel4/configure
===================================================================
--- stunnel4.orig/configure
+++ stunnel4/configure
@@ -11536,7 +11536,7 @@
 #define HAVE_LIBZ 1
 _ACEOF
 
-  LIBS="-lz $LIBS"
+#  LIBS="-lz $LIBS"
 
 fi
 
