Dynamically load the vulkan library in our test tools

Bug: skia:
Change-Id: I7c1f6cbb2b50ca284f40cf4b9ef49a76083b38c6
Reviewed-on: https://skia-review.googlesource.com/68643
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
9 files changed