[libcxx] [test] Use the native path types in path.compare

This makes sure that it actually tests the right compare() overloads
in windows configurations.

This also fixes the allocation guards that enforce no allocations
while running the compare() functions.

Differential Revision: https://reviews.llvm.org/D97551

GitOrigin-RevId: 74c883f7e5ba9143e51c2a68203e324511eb63a0
1 file changed