Clean up EGL thread state at thread exit in nanobench and DM

include/gpu/gl/SkGLContext.h

Index: include/gpu/gl/SkGLContext.h
diff --git a/include/gpu/gl/SkGLContext.h b/include/gpu/gl/SkGLContext.h
index ddf5dc080a113ec648e9b94409184e22eda21610..217212219256243bc7d456b15e422140a2df646b 100644
--- a/include/gpu/gl/SkGLContext.h
+++ b/include/gpu/gl/SkGLContext.h
@@ -131,6 +131,11 @@ private:
 SK_API SkGLContext* SkCreatePlatformGLContext(GrGLStandard forcedGpuAPI,
                                               SkGLContext* shareContext = nullptr);
 
+/** Destroys any GL related thread global state that may have been created due
+ *  to calls to SkCreatePlatformGLContext.
+ */
+SK_API void SkReleasePlatformGLAPIsInThread();
+
 /**
  * Helper macros for using the GL context through the GrGLInterface. Example:
  * SK_GL(glCtx, GenTextures(1, &texID));