[CUDA] Fix output from `ptxas` being removes as a temporary file

Summary:
The logic here is to add the `.cubin` temporary file if we had to create
a new filename to handle it. Unfortuantely the logic was wrong because
we compare `const char *` values here. This logic seems to have been
wrong for some time, but was never noticed since we never used the
relocatable output.

Fixes https://github.com/llvm/llvm-project/issues/60301