Deleting void pointers is bad, mmmkay?

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2129483003

Review-Url: https://codereview.chromium.org/2129483003

src/gpu/vk/GrVkBuffer.cpp

@@ -153,7 +153,7 @@ void GrVkBuffer::vkUnmap(GrVkGpu* gpu) {
         VK_CALL(gpu, UnmapMemory(gpu->device(), this->alloc().fMemory));
     } else {
         gpu->updateBuffer(this, fMapPtr, this->size());
-        delete fMapPtr;
+        delete (unsigned char*) fMapPtr;
     }
 
     fMapPtr = nullptr;