Common vars check should account for OPpTARGET_MY

When checking for common vars on either side of a list assignment (to
see whether we need to make temporary copies), we need to account for
the OPpTARGET_MY optimisation which transforms ‘$lex = $foo . $bar’
into a simple ‘$foo . $bar’ that writes directly to $lex instead of
writing to a scratch variable and returning that.

This was printing foofoo instead of foobar:

$ ./perl -Ilib -le 'my ($a,$b); $foo="foo"; $bar="bar"; ($a,$b) = ($b=$foo."", $a=$bar.""); print $a,$b'
Skip over state declarations at run time
Tweak multiple nextstate optimisation further

There was still one niggling nulled nextstate in the execution
sequence in cases like this (the one numbered 4):

$ ./perl -Ilib  -MO=Concise -e 'time; our $x; our $y; time'
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
3     <0> time[t1] v ->4
-     <0> ex-nextstate v ->5
-     <1> rv2sv vK/OURINTR,1 ->4
-        <$> gv(*x) s ->-
4     <0> ex-nextstate v ->5
-     <1> rv2sv vK/OURINTR,1 ->5
-        <$> gv(*y) s ->-
5     <;> nextstate(main 3 -e:1) v:{ ->6
6     <0> time[t4] v ->7
-e syntax OK
perldelta for 412989c
Update perlfaq to version 5.015046
perldelta entry for update to perlfaq
Add blank line after =item
More perldelta work
Remove unused stubs and editing notes from perldelta.
Update Stevan Little's email address
perldelta: Typo, clarification
perlvar: Note a deprecation
Another perldelta entry
Replace "message" with the actual message.

Otherwise, the formatted delta will just list "message" when listing
new errors, instead of the actual messages.
An error cannot be both new, and reworded.
Fix spelling in perldelta

Using ispell. Ispell does complain about "Acknowledgements", suggesting
"Acknowledgments", but Merriam-Webster recognizes "Acknowledgements" as
a valid variation.
perldelta: Mention that IRIX and Tru64 are regained platforms.
perldelta: Update the Inf and Nan entry.

jhi says properly explaining the long-double and double-double requires
much more detail, so he suggested dropping mentioning it.
Fix crash with ‘join,’ caused by 987c96916
IRIX: fsync documented to fail on read-only filehandles.