tmate: fix build against msgpack-c 6.0

This patch is taken from
https://git.alpinelinux.org/aports/commit/?id=f923597f4bdea424dc28b1d026269df060596fac

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>

net/tmate/Makefile

@@ -6,7 +6,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=tmate
 PKG_VERSION:=2.4.0
-PKG_RELEASE:=$(AUTORELEASE)
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/tmate-io/tmate/tar.gz/$(PKG_VERSION)?

net/tmate/patches/020-msgpack-c.patch

@@ -0,0 +1,11 @@
+--- a/configure.ac
++++ b/configure.ac
+@@ -201,7 +201,7 @@ fi
+ 
+ PKG_CHECK_MODULES(
+   MSGPACK,
+-  msgpack >= 1.1.0,
++  msgpack-c >= 1.1.0,
+   [
+     CPPFLAGS="$MSGPACK_CFLAGS $CPPFLAGS"
+     LIBS="$MSGPACK_LIBS $LIBS"