The CMake build derives the .def name from the project name, which is
libvk_swiftshader.

Bug b/115344057
Bug b/116336664

Change-Id: I236839b2da4531e01f5260705c189d9ae8df9769
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27988
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>