Pre-init virglrenderer only when tracing is disabled, otherwise perfetto
might get confused. Do a vkEnumerateInstanceExtensionProperties to
preload Vulkan ICDs.
"time for i in `seq 100`; do vulkaninfo > /dev/null; done" goes from
0m5.895s to 0m5.535s.
Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-by: Ryan Neph <ryanneph@google.com>
Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>