dev-libs/mtxclient: fix build with libfmt 11

Signed-off-by: Anna (cybertailor) Vyalkova <cyber+gentoo@sysrq.in>

dev-libs/mtxclient/files/mtxclient-0.10.0-fmt11.patch

@@ -0,0 +1,49 @@
+From 4a4726c77123f805cff8b954909663eaed296558 Mon Sep 17 00:00:00 2001
+From: Kefu Chai <tchaikov@gmail.com>
+Date: Mon, 15 Jul 2024 11:35:09 +0800
+Subject: [PATCH] Fix build with fmt 11
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+fmt 11 enforces that fmt::formatter<..>::format() should be const.
+otherwise the tree does not build:
+
+```
+/usr/include/fmt/base.h:1392:29: error: passing ‘const fmt::v11::formatter<std::optional<mtx::http::ClientError> >’ as ‘this’ argument discards qualifiers [-fpermissive]
+ 1392 |     ctx.advance_to(cf.format(*static_cast<qualified_type*>(arg), ctx));
+      |                    ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+```
+
+so let's mark the `format()` with `const` specifier.
+
+Signed-off-by: Kefu Chai <tchaikov@gmail.com>
+---
+ include/mtxclient/http/errors.hpp | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/include/mtxclient/http/errors.hpp b/include/mtxclient/http/errors.hpp
+index 2d0e7a4..b99ff90 100644
+--- a/include/mtxclient/http/errors.hpp
++++ b/include/mtxclient/http/errors.hpp
+@@ -87,7 +87,7 @@ struct fmt::formatter<mtx::http::ClientError>
+     // Formats the point p using the parsed format specification (presentation)
+     // stored in this formatter.
+     template<typename FormatContext>
+-    auto format(const mtx::http::ClientError &e, FormatContext &ctx) -> decltype(ctx.out())
++    auto format(const mtx::http::ClientError &e, FormatContext &ctx) const -> decltype(ctx.out())
+     {
+         // ctx.out() is an output iterator to write to.
+         bool prepend_comma = false;
+@@ -132,7 +132,7 @@ struct fmt::formatter<std::optional<mtx::http::ClientError>> : formatter<mtx::ht
+ {
+     // parse is inherited from formatter<string_view>.
+     template<typename FormatContext>
+-    auto format(std::optional<mtx::http::ClientError> c, FormatContext &ctx)
++    auto format(std::optional<mtx::http::ClientError> c, FormatContext &ctx) const
+     {
+         if (!c)
+             return fmt::format_to(ctx.out(), "(no error)");
+-- 
+2.47.1
+