linux build: add MSDN COM __interface replacement

Author: eagleivg

src/xrCore/_types.h

@@ -72,5 +72,7 @@ using string_path = char[2 * max_path];
 // XXX: Replace __interface with either struct or class. MS defines it as struct for COM, but this project is C++.
 #if defined(WINDOWS)
 #define xr_pure_interface __interface
+#elif defined(LINUX)
+#define xr_pure_interface struct
 #endif
 #endif

src/xrEngine/xr_object.h

@@ -26,9 +26,7 @@ class CInifile;
 #define CROW_RADIUS2 (60.f)
 
 class IPhysicsShell;
-#if defined(WINDOWS)
 xr_pure_interface IObjectPhysicsCollision;
-#endif
 
 class CAttachmentOwner;
 class CInventoryOwner;
@@ -188,9 +186,7 @@ class IGameObject : public virtual IFactoryObject,
     virtual IRenderVisual* Visual() const = 0;
     virtual void OnChangeVisual() = 0;
     virtual IPhysicsShell* physics_shell() = 0;
-#if defined(WINDOWS)
     virtual const IObjectPhysicsCollision* physics_collision() = 0;
-#endif
     // Name management
     virtual shared_str cName() const = 0;
     virtual void cName_set(shared_str N) = 0;

src/xrGame/PhysicsShellHolder.h

@@ -47,7 +47,7 @@ class CPhysicsShellHolder : public CGameObject,
     virtual bool ActivationSpeedOverriden(Fvector& dest, bool clear_override) { return false; }
     IC CPhysicsShell*& PPhysicsShell() { return m_pPhysicsShell; }
     IC CPhysicsShellHolder* PhysicsShellHolder() { return this; }
-    virtual const IObjectPhysicsCollision* physics_collision();
+    virtual const IObjectPhysicsCollision* physics_collision() {}
     virtual const IPhysicsShell* physics_shell() const;
     virtual IPhysicsShell* physics_shell();
     virtual const IPhysicsElement* physics_character() const;