fix a rare swapchain leak in PlatformEGL (#9348)

If createSwapChain() fails, a SwapChain object is always returned
(this might itself be a problem, but we can address that later),
however in that case, destroySwapChain() would leak the EGLSwapChain
structure.

filament/backend/src/opengl/platforms/PlatformEGL.cpp

@@ -618,8 +618,8 @@ void PlatformEGL::destroySwapChain(SwapChain* swapChain) noexcept {
             // - this is actually a bit too aggressive, but it is a rare operation.
             egl.makeCurrent(mEGLDummySurface, mEGLDummySurface);
             eglDestroySurface(mEGLDisplay, sc->sur);
-            delete sc;
         }
+        delete sc;
     }
 }