* test-suite/standalone/test-pthread-create.c (inner_main): New
function.
(main): Call it within `scm_with_guile', instead of using
`scm_init_guile'. This improves portability--e.g.,
`GC_get_stack_base', used by `scm_init_guile', failed on Darwin
up to BDW-GC 7.1alpha4 included (thanks, Mark, for the hint.)