* inftarg.c (child_create_inferior, child_attach,
child_mourn_inferior): collect unix child process stratum
functions which live below the target vector into this file to
facilitate host/target/native split. Also, make them static.
* inflow.c (child_mourn_inferior): removed.
* infrun.c (child_create_inferior, child_attach): removed.
(resume): becomes global so that functions below the
target vector can find it.
* inferior.h (resume): add prototype.
(child_mourn_inferior, child_create_inferior, child_attach):
remove prototypes.