This avoids a collision between the directories we use when compiling
multiple ways, which in turn leads to a race condition in parallel
builds.
output_fn <- get_output_fn dflags StopLn maybe_loc
let base_o = dropExtension output_fn
output_fn <- get_output_fn dflags StopLn maybe_loc
let base_o = dropExtension output_fn
- split_odir = base_o ++ "_split"
+ split_odir = base_o ++ "_" ++ osuf ++ "_split"
createDirectoryHierarchy split_odir
createDirectoryHierarchy split_odir