[Flang] Remove tests checking now removed 'libc-gpu.a`

Summary:
These tests were removed in a previous patch.

The linker wrapper now just extracts the device inputs and forwards them
directly to the device's link job. This is the job that occurs when you
do `clang --target=amdgcn-amd-amdhsa foo.o` or similar. Because this can
handle LTO we no longer do LTO in the linker wrapper. This has some
fallout, because we now require `ld.lld` to be built with a compatible
version, but I think we always expected that.

I made the decision to remove this `libc-gpu.a` library because it was
unnecessary and complicated things. Now I simply have the link job
implicitly link `-lc` if it exists. Users can also now pass
`-Xoffload-linker=amdgcn-amd-amdhsa -lc` or similar to pass it. Because
of this, these tests need to be removed. I forgot that Fortran also had
these.

0 files changed, 0 insertions, 0 deletions