Vulkan: Make sure program's pipeline cache is created The condition to create or use the program's pipeline cache has become quite complicated. This change simplifies things by making sure the pipeline cache is created if and when it's used, instead of guessing how it will be used and pre-create it. Bug: angleproject:7369 Change-Id: I7f3558e55f391da8c701e359d2f88d248c820de4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4076508 Reviewed-by: Yuxin Hu <yuxinhu@google.com> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>