* stime.c, socket.c, simpos.c, procs.c, posix.c, ports.c,

* stime.c, socket.c, simpos.c, procs.c, posix.c, ports.c,
net_db.c, fports.c, filesys.c, eval.c, deprecation.c, dynl.c:
Replaced uses of SCM_STRING_CHARS with proper uses of
scm_to_locale_string.  Replaced SCM_STRINGP with scm_is_string.
Replaced scm_mem2string with scm_from_locale_string.

* simpos.c, posix.c (allocate_string_pointers, environ_list_to_c):
Removed, replaced all uses with scm_i_allocate_string_pointers.