Move Perl5Array refcnt inc to C code

lib/Inline/Perl5.pm6

@@ -106,6 +106,9 @@ sub p5_sv_to_char_star(Perl5Interpreter, Pointer) is native($p5helper)
 sub p5_sv_to_av(Perl5Interpreter, Pointer) is native($p5helper)
     returns Pointer { ... }
 
+sub p5_sv_to_av_inc(Perl5Interpreter, Pointer) is native($p5helper)
+    returns Pointer { ... }
+
 sub p5_sv_to_hv(Perl5Interpreter, Pointer) is native($p5helper)
     returns Pointer { ... }
 
@@ -570,7 +573,7 @@ method !p5_hash_to_writeback_p6_hash(Pointer $sv) {
 }
 
 method !p5_array_to_writeback_p6_array(Pointer $sv) {
-    my Pointer $av = p5_sv_to_av($!p5, $sv);
+    my Pointer $av = p5_sv_to_av_inc($!p5, $sv);
 
     Perl5Array.new(ip5 => self, p5 => $!p5, :$av)
 }

p5helper.c

@@ -198,6 +198,12 @@ AV *p5_sv_to_av(PerlInterpreter *my_perl, SV* sv) {
     return (AV *) SvRV(sv);
 }
 
+AV *p5_sv_to_av_inc(PerlInterpreter *my_perl, SV* sv) {
+    AV * const retval = (AV *) SvRV(sv);
+    SvREFCNT_inc((SV *)retval);
+    return retval;
+}
+
 HV *p5_sv_to_hv(PerlInterpreter *my_perl, SV* sv) {
     return (HV *) SvRV(sv);
 }