Tests: Fix CudaOnly.SeparateCompilationPTX test project name
Fix the test added by !6594 (merged) to have a project()
name matching what
is passed to CTest's --build-project
option. Otherwise, on
VS builds, MSBuild warns:
MSBUILD : error MSB1009: Project file does not exist.
Other CUDA tests use a matching project name already.
Backport: release