vk_pipeline_cache: cap boot builds when no used list exists yet

Without vulkan_used.bin (the first boot with this change, or a session
that ended before saving it) every cached graphics pipeline was still
built at boot. A Linux tester's cache had grown to 47,951 pipelines over
many builds: ~21 GB of driver memory built before the game started,
filling RAM and swap. The list is only saved at exit or after two
minutes, so a boot that ran out of memory never saved one and the next
boot did the same.

Build at most 3,000 cached graphics pipelines at boot in that case and
the rest when first needed; the next session uses the saved list.
EDEN_NX2_PRELOAD_ALL_PIPELINES=1 still builds all of them.

0 files changed, 0 insertions, 0 deletions