Ports: Add GemRB

GemRB is an open-source implementation of the Infinity engine by
Bioware, used in some of their classic role-playing games.

Ports/gemrb/patches/0001-Hard-code-some-paths-for-runtime-purposes.patch

@@ -0,0 +1,30 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Julian=20Offenh=C3=A4user?= <offenhaeuser@protonmail.com>
+Date: Sat, 11 Feb 2023 00:05:55 +0100
+Subject: [PATCH] Hard-code some paths for runtime purposes
+
+GemRB uses the paths where its libraries and data are copied to during
+installation at runtime by generating a header. This does not work for
+us, as our paths change from compilation to runtime. The easiest fix for
+this is to hard-code these paths in the header file.
+---
+ cmake/cmake_config.h.in | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/cmake/cmake_config.h.in b/cmake/cmake_config.h.in
+index 17584b33da6e9cc610d8be7d1a4f28b8b587844a..02a6214f4215723eb4c90b65f67aea6d508be193 100644
+--- a/cmake/cmake_config.h.in
++++ b/cmake/cmake_config.h.in
+@@ -10,9 +10,9 @@
+ #cmakedefine HAVE_MEMALIGN 1
+ #cmakedefine HAVE_ALIGNED_MALLOC 1
+ #cmakedefine HAVE_POSIX_MEMALIGN 1
+-#cmakedefine PLUGIN_DIR "${PLUGIN_DIR}"
+-#cmakedefine DATA_DIR "${DATA_DIR}"
+-#cmakedefine SYSCONF_DIR "${SYSCONF_DIR}"
++#cmakedefine PLUGIN_DIR "/usr/local/lib/gemrb/plugins/"
++#cmakedefine DATA_DIR "/usr/local/share/gemrb/"
++#cmakedefine SYSCONF_DIR "/usr/local/etc/gemrb/"
+ #cmakedefine NO_COLOR ${NOCOLOR}
+ #cmakedefine OPENGL_BACKEND ${OPENGL_BACKEND}
+ #cmakedefine NOFPSLIMIT ${NOFPSLIMIT}