Adjust CV::save logic for perl522

[atoomic]

This is fixing the compilation of several core tests
and introduced only one single regression with unicode sub.

This is fixing several errors from the test coresuite, including 3 segfaults.
only introducing one single regression [uni/parser.t] for unicode subs
which is not really critical for now.

> g diff -U0 | grep -v '@@'
diff --git a/t/v5.22.0/C-COMPILED/known_errors.txt b/t/v5.22.0/C-COMPILED/known_errors.txt
index b972873..e969d49 100644
--- a/t/v5.22.0/C-COMPILED/known_errors.txt
+++ b/t/v5.22.0/C-COMPILED/known_errors.txt
-io/open.t                    PLAN      Plan was valid
-io/print.t                   PLAN      Plan was valid
-io/read.t                    PLAN      Plan was valid
-io/say.t                     PLAN      Plan was valid
+io/open.t                    TESTS     Test results:
-op/anonconst.t               SIG       Exit signal is 11 SEGV
-op/const-optree.t            SIG       Exit signal is 11 SEGV
+op/const-optree.t            PLAN      Plan was valid
-op/gv.t                      TESTS     Test results:
-op/index.t                   TESTS     Test results:
-op/my_stash.t                TESTS     Test results:
-op/smartmatch.t              TESTS     Test results:
-op/sub.t                     SIG       Exit signal is 11 SEGV
-op/taint.t                   TESTS     Test results:
-uni/gv.t                     TESTS     Test results:
-uni/lex_utf8.t               TESTS     Test results:
+uni/parser.t                 TESTS     Test results:
-xtestc/0203.t                TESTS     Output is: "encoding(cp1252)unixperlioutf8" expect "ok"
-xtestc/0229.t                TESTS     Output is: "" expect "ok"
-xtestc/0246.t                TESTS     Output is: "" expect "ok"
-xtestc/0305.t                TESTS     Output is: "" expect "ok"

extract from uni/parser.t [regression]

 sub 原 () { 1 }
 is grep({ $_ eq "\x{539f}"     } keys %::), 1, "Constant subs generate the right glob.";

[rurban]

Principly ok, just see the errors. SVs_PADSTALE needs to be defined.

[atoomic]

add patch for SVs_PADSTALE to define it when it's not ( < 5.8.5 )