Make context not-current after rendering to prevent "already connecte…

…d" on ANGLE

Some phones no longer have a native (E)GL implementation but use
ANGLE on top of Vulkan, which is more strict about Vulkan/NativeWindow
surfaces that have lingering references from an existing EGL Surface.
This is especially problematic with this app that simply recreates the
EGL surface every time the callback is called, e.g. in surface creation,
"change", and resize:

  E  [SurfaceView[rust.androidnativesurface/rust.androidnativesurface.MainActivity]@0#1(BLAST Consumer)1](id:5c2300000001,api:1,p:23587,c:23587) connect: already connected (cur=1 req=1)
  E  native_window_api_connect() failed: Invalid argument (-22)
  D  ANGLE Info:Debug.cpp:490 (insertMessage): EGL ERROR: eglPlatformCreateWindowSurface: Internal Vulkan error (-1000000001): The requested window is already connected to a VkSurfaceKHR, or to some other non-Vulkan API, in ../../src/libANGLE/renderer/vulkan/android/WindowSurfaceVkAndroid.cpp, createSurfaceVk:133.
  I  thread '<unnamed>' panicked at src/support.rs:36:78:
  I  called `Result::unwrap()` on an `Err` value: Error { raw_code: Some(12301), raw_os_message: None, kind: BadSurface }

This is simply fixed by un-currentling the current context and the
surface associated with it.

android_native_surface/src/lib.rs

@@ -83,7 +83,14 @@ fn render_to_native_window(window: NativeWindow) {
 
     renderer.draw();
 
-    gl_window.surface.swap_buffers(&gl_context).unwrap();
+    gl_window
+        .surface
+        .swap_buffers(&gl_context)
+        .expect("Cannot swap buffers");
+
+    gl_context
+        .make_not_current()
+        .expect("Cannot uncurrent GL context");
 }
 
 #[no_mangle]