* builds/unix/configure.ac, builds/unix/unix-cc.in,
        builds/unix/unix-def.in: small fix to configure sub-system on Unix
        to allow other programs to correctly link with zlib when needed
diff --git a/builds/unix/configure.ac b/builds/unix/configure.ac
index 44baa74..b9c8fbd 100644
--- a/builds/unix/configure.ac
+++ b/builds/unix/configure.ac
@@ -90,10 +90,12 @@
 fi
 if test x$with_zlib != xno && test -n "$LIBZ"; then
   CFLAGS="$CFLAGS -DFT_CONFIG_OPTION_SYSTEM_ZLIB"
+  LDFLAGS="$LDFLAGS $LIBZ"
   SYSTEM_ZLIB=yes
 fi
 AC_SUBST(LIBZ)
 AC_SUBST(CFLAGS)
+AC_SUBST(LDFLAGS)
 AC_SUBST(SYSTEM_ZLIB)