From 2b584fffce0e1055937ec820e3e5d0954277efe7 Mon Sep 17 00:00:00 2001
From: Viktor Szakats <commit@vsz.me>
Date: Mon, 5 Dec 2022 14:31:32 +0000
Subject: [PATCH] Makefile.mk: improve a GNU Make hack [ci skip]

Replace the hack of using `$() ` to represent a single space. The new
method silences the `--warn-undefined-variables` debug warning and it's
also a better-known form of solving this problem.

Reviewed-by: Jay Satiro
Closes #10031
---
 lib/Makefile.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/Makefile.mk b/lib/Makefile.mk
index efd4ba4202..56917e0201 100644
--- a/lib/Makefile.mk
+++ b/lib/Makefile.mk
@@ -324,7 +324,7 @@ ifdef WIN32
   _LIBS += -lws2_32 -lcrypt32 -lbcrypt
 endif
 
-ifneq ($(findstring 11,$(subst $() ,,$(SSLLIBS))),)
+ifneq ($(findstring 11,$(subst $(subst ,, ),,$(SSLLIBS))),)
   CPPFLAGS += -DCURL_WITH_MULTI_SSL
 endif
 
-- 
2.47.3