Fix crash in OpenBSD framebuffer/texture cleanup.

- It seems that textures must be destroyed *before* the renderer is destroyed
- This isn't mentioned anywhere in the SDL docs, and it works everywhere else, but in any event it is now fixed

src/common/FBSurfaceSDL2.cxx

@@ -37,7 +37,10 @@ FBSurfaceSDL2::FBSurfaceSDL2(FrameBufferSDL2& buffer,
 FBSurfaceSDL2::~FBSurfaceSDL2()
 {
   if(mySurface)
+  {
     SDL_FreeSurface(mySurface);
+    mySurface = nullptr;
+  }
 
   free();
 }

src/common/FrameBufferSDL2.cxx

@@ -59,6 +59,12 @@ FrameBufferSDL2::~FrameBufferSDL2()
 
   if(myRenderer)
   {
+    // Make sure to free surfaces/textures before destroying the renderer itself
+    // Most platforms are fine with doing this in either order, but it seems
+    // that OpenBSD in particular crashes when attempting to destroy textures
+    // *after* the renderer is already destroyed
+    freeSurfaces();
+
     SDL_DestroyRenderer(myRenderer);
     myRenderer = nullptr;
   }

src/emucore/FrameBuffer.cxx

@@ -555,6 +555,20 @@ shared_ptr<FBSurface> FrameBuffer::allocateSurface(int w, int h, const uInt32* d
   return mySurfaceList.at(mySurfaceList.size() - 1);
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void FrameBuffer::freeSurfaces()
+{
+  for(auto& s: mySurfaceList)
+    s->free();
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void FrameBuffer::reloadSurfaces()
+{
+  for(auto& s: mySurfaceList)
+    s->reload();
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void FrameBuffer::resetSurfaces()
 {
@@ -564,10 +578,8 @@ void FrameBuffer::resetSurfaces()
   // Any derived FrameBuffer classes that call this method should be
   // aware of these restrictions, and act accordingly
 
-  for(auto& s: mySurfaceList)
-    s->free();
-  for(auto& s: mySurfaceList)
-    s->reload();
+  freeSurfaces();
+  reloadSurfaces();
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/FrameBuffer.hxx

@@ -352,6 +352,16 @@ class FrameBuffer
     virtual unique_ptr<FBSurface>
         createSurface(uInt32 w, uInt32 h, const uInt32* data) const = 0;
 
+    /**
+      Calls 'free()' on all surfaces that the framebuffer knows about.
+    */
+    void freeSurfaces();
+
+    /**
+      Calls 'reload()' on all surfaces that the framebuffer knows about.
+    */
+    void reloadSurfaces();
+
     /**
       Grabs or ungrabs the mouse based on the given boolean value.
     */
@@ -386,8 +396,7 @@ class FrameBuffer
     void drawMessage();
 
     /**
-      Issues a 'free' and 'reload' instruction to all surfaces that the
-      framebuffer knows about.
+      Frees and reloads all surfaces that the framebuffer knows about.
     */
     void resetSurfaces();