Extension checking in vkCreateInstance would simply
loop through the first extension requested. This
bug did not show up earlier (or at all) because
erroneous situations would cause early exits in
the loader.

Bug: b/125943360
Change-Id: Id664f46d09dce1b3530670ae826314b26797b5be
Reviewed-on: https://swiftshader-review.googlesource.com/c/25368Tested-by: Hernan Liatis <hliatis@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>