make pp_leavesublv use S_leavesub_adjust_stacks()

Currently S_leavesub_adjust_stacks() is just used by pp_leavesub.
Rename it to Perl_leave_adjust_stacks(), extend its functionality
slightly, then make pp_leavesublv() use it too.

This means that lvalue sub exit gains the benefit of FREETMPS being done,
and (where mortal copying needs doing) the optimised copying code.
It also means there is now one less version of the "process args on scope
exit" code.

pp_leavesublv() still does a scan of its return args looking for things to
croak() on, but leaves everything else to leave_adjust_stacks().

leave_adjust_stacks() is intended shortly to be used in place of
S_leave_common() too, thus unifying all args-on-scope-exit code.

The changes to leave_adjust_stacks() in this commit (apart from the
renaming and doc changes) are:
* a new arg to indicate what condition to use to decide whether to
  pass or copy the arg;
* a new branch to mortalise and ref count bump an arg

1 files changed, 2 insertions, 0 deletions

diff --git a/embed.fnc b/embed.fnc
index 61509f0b7c..b8c5810315 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -2878,4 +2878,6 @@ Ei	|STRLEN	|sv_or_pv_pos_u2b|NN SV *sv|NN const char *pv|STRLEN pos \
 EMpPX	|SV*	|_get_encoding
 Xp	|void	|clear_defarray	|NN AV* av|bool abandon
 
+ApM	|void	|leave_adjust_stacks|NN SV **base_sp|I32 gimme|int filter
+
 : ex: set ts=8 sts=4 sw=4 noet: