From: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
Date: Sun, 5 Mar 2023 20:58:13 +0800
Subject: Fix finding msgpack 6+

tmate FTBFS with the 6.x version of the msgpack C library. Upstream
renamed the library from libmsgpackc to libmsgpack-c and the pkg-config
file from msgpack.pc to msgpack-c.pc, so any checks for the presence of
the library at build time should handle both names.

Co-authored-by: Sam James <sam@gentoo.org>

Origin: backport, https://github.com/tmate-io/tmate/pull/281
---
diff --git a/configure.ac b/configure.ac
index 2035470f..6e89685b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -199,7 +199,19 @@ PKG_CHECK_MODULES(
     LIBS="$MSGPACK_LIBS $LIBS"
     found_msgpack=yes
   ],
-  found_msgpack=no
+  [
+    # msgpack.pc was renamed to msgpack-c.pc in 6.0.0.
+    PKG_CHECK_MODULES(
+      MSGPACKC,
+      msgpack-c >= 1.2.0,
+      [
+        CPPFLAGS="$MSGPACKC_CFLAGS $CPPFLAGS"
+        LIBS="$MSGPACKC_LIBS $LIBS"
+        found_msgpack=yes
+      ],
+      found_msgpack=no
+    )
+  ],
 )
 if test "x$found_msgpack" = xno; then
   AC_MSG_ERROR("msgpack >= 1.2.0 not found")