libcurl: Don't disable OpenSSL by default (#6281)

#5970 didn't work because default value was set to false

packages/l/libcurl/xmake.lua

@@ -19,9 +19,9 @@ package("libcurl")
     add_patches("8.9.0", path.join(os.scriptdir(), "patches", "8.9.0", "fix-apple-sdk-bug.patch"), "9503db07a76d828ab7d33565c6aa65c9df80626c11248a4b670aaf10b42e4de7")
 
     add_configs("cares",    {description = "Enable c-ares support.", default = false, type = "boolean"})
-    add_configs("openssl",  {description = "Enable OpenSSL for SSL/TLS.", default = false, type = "boolean"})
-    add_configs("openssl3", {description = "Enable OpenSSL-3 for SSL/TLS.", default = false, type = "boolean"})
-    add_configs("mbedtls",  {description = "Enable mbedTLS for SSL/TLS.", default = false, type = "boolean"})
+    add_configs("openssl",  {description = "Enable OpenSSL for SSL/TLS.", default = nil, type = "boolean"})
+    add_configs("openssl3", {description = "Enable OpenSSL-3 for SSL/TLS.", default = nil, type = "boolean"})
+    add_configs("mbedtls",  {description = "Enable mbedTLS for SSL/TLS.", default = nil, type = "boolean"})
     add_configs("nghttp2",  {description = "Use Nghttp2 library.", default = false, type = "boolean"})
     add_configs("openldap", {description = "Use OpenLDAP library.", default = false, type = "boolean"})
     add_configs("libidn2",  {description = "Use Libidn2 for IDN support.", default = false, type = "boolean"})