To the best of my knowledge there is not a single mention of sunglasses in the books. Additionally, there are times when the glaring sun is specifically mentioned as an issue and yet we still find no mention of sunglasses. For example, in Chapter Nineteen of Half-Blood Prince the sun affects Quidditch performance:
There was little wind; the clouds were patchy; every now and then there were dazzling flashes of bright sunlight.
"Tricky conditions!" McLaggen said bracingly to the team. "Coote, Peakes, you'll want to fly out of the sun, so they don't see you coming —"
"I'm the Captain, McLaggen, shut up giving them instructions," said Harry angrily. "Just get up by the goal posts!"
Once McLaggen had marched off, Harry turned to Coote and Peakes.
"Make sure you do fly out of the sun," he told them grudgingly.
In Chapter Thirty at Dumbledore's funeral we find the following:
Ron's face was screwed up as though the sun was blinding him.
(Though it is possible that "as though" means that the sun wasn't actually blinding him, and it might have been a cover for crying.)
In the Quidditch match in Chapter Nineteen of Order of the Phoenix as well the sun is mentioned as a factor that could affect performance:
There was no wind at all and the sky was a uniform pearly white, which meant that visibility would be good without the drawback of direct sunlight in the eyes.
Likewise in Chapter Fifteen of Prisoner of Azkaban:
"Okay — no wind to speak of — sun's a bit bright, that could impair your vision, watch out for it — ground's fairly hard, good, that'll give us a fast kickoff — "
That we still find no mention of sunglasses even in such instances may indicate that wizards would not normally use them. Of course, it is also possible that people were wearing sunglasses but it wasn't an important enough detail to be mentioned. However, at the very least the Quidditch players probably weren't using sunglasses, as if they had been there would be less concern for the sun.