transmission: Use external libminiupnpc instead of internal.

The original patch that forced internal usage hid an actual issue in the build system. Replace patch with upstream one.

Also reorganized the Makefile a bit and removed some cruft.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/transmission/patches/020-fix-external-miniupnpc.patch

@@ -0,0 +1,35 @@
+From 94fa0bba88740b9ab58c5805ddb24b05b2635f34 Mon Sep 17 00:00:00 2001
+From: Mike Gelfand <mikedld@mikedld.com>
+Date: Fri, 26 Jan 2018 08:31:16 +0300
+Subject: [PATCH] Fix FTCBFS due to AC_RUN_IFELSE (patch by Helmut Grohne)
+
+Fixes: #475
+---
+ configure.ac | 8 +++-----
+ 1 file changed, 3 insertions(+), 5 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index cb026df..335f4a7 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -390,14 +390,12 @@ dnl Let's hope it's 1.7 or higher, since it provides
+ dnl MINIUPNPC_API_VERSION and we won't have to figure
+ dnl it out on our own
+ if test "x$upnp_version" = "xunknown" ; then
+-  AC_RUN_IFELSE(
++  AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM(
+       [#include <stdlib.h>
+        #include <miniupnpc/miniupnpc.h>],
+-      [#ifdef MINIUPNPC_API_VERSION
+-       return EXIT_SUCCESS;
+-       #else
+-       return EXIT_FAILURE;
++      [#ifndef MINIUPNPC_API_VERSION
++       #error MINIUPNPC_API_VERSION undefined
+        #endif]
+     )],
+     [upnp_version=">= 1.7"]
+-- 
+2.7.4
+

net/transmission/patches/020-use-internal-miniupnp.patch

@@ -1,13 +0,0 @@
-diff --git a/configure.ac b/configure.ac
-index aff673b..7e109af 100644
---- a/configure.ac
-+++ b/configure.ac
-@@ -378,7 +378,7 @@ dnl See if ANY version of miniupnpc is installed
- AC_LINK_IFELSE(
-   [AC_LANG_PROGRAM([#include <miniupnpc/miniupnpc.h>],
-                    [struct UPNPDev dev;])],
--  [upnp_version="unknown"],
-+  [upnp_version="none"],
-   [upnp_version="none"]
- )
-