Allow overriding OGRE_PLUGIN_DIR in cmake command line

CMakeLists.txt

@@ -325,12 +325,14 @@ else ()
     add_definitions(-DOGRE_PLUGIN_DEBUG_SUFFIX="_d")
 endif()
 
-add_definitions(-DOGRE_PLUGIN_DIR_REL="${OGRE_PLUGIN_DIR_REL}")
-add_definitions(-DOGRE_PLUGIN_DIR_DBG="${OGRE_PLUGIN_DIR_DBG}")
 if (APPLE AND OPENMW_OSX_DEPLOYMENT)
     # make it empty so plugin loading code can check this and try to find plugins inside app bundle
     add_definitions(-DOGRE_PLUGIN_DIR="")
 else()
+    if (NOT DEFINED ${OGRE_PLUGIN_DIR})
+        set(OGRE_PLUGIN_DIR ${OGRE_PLUGIN_DIR_REL})
+    endif()
+
     add_definitions(-DOGRE_PLUGIN_DIR="${OGRE_PLUGIN_DIR}")
 endif()
 

components/ogreinit/ogreinit.cpp

@@ -193,7 +193,7 @@ namespace OgreInit
                 pluginDir = Ogre::macFrameworksPath();
     #endif
     #if OGRE_PLATFORM == OGRE_PLATFORM_LINUX
-            pluginDir = OGRE_PLUGIN_DIR_REL;
+            pluginDir = OGRE_PLUGIN_DIR;
     #endif
         }
         Files::loadOgrePlugin(pluginDir, "RenderSystem_GL", *mRoot);