girparser: fixes to (out caller-allocates) handling

• Default to (transfer none) in accordance with documentation (see "Default annotations" section at the end).
• Do not mark refcounted parameters as ref/out to avoid extra indirection
  Docs are somewhat less clear on this one, but this is what you'd expect "caller-allocated array/refcounted type" to mean.

Fixes #771. I'd appreciate testing this with more packages to ensure nothing breaks.