Allow mro_isa_changed_in to be called on nonexistent packages

This is necessary for an upcoming bug fix.

(For this bug:

 @left::ISA = 'outer::inner';
 @right::ISA = 'clone::inner';
 *clone:: = \%outer::;
 print left->isa('clone::inner'),"\n";
 print right->isa('outer::inner'),"\n";

)

This commit actually replaces mro_isa_changed_in with
mro_isa_changed_in3. See the docs for it in the diff for mro.c.

1 files changed, 7 insertions, 0 deletions

diff --git a/mathoms.c b/mathoms.c
index 78516b3d4b..152a64c089 100644
--- a/mathoms.c
+++ b/mathoms.c
@@ -83,6 +83,7 @@ PERL_CALLCONV I32 Perl_my_lstat(pTHX);
 PERL_CALLCONV I32 Perl_sv_eq(pTHX_ register SV *sv1, register SV *sv2);
 PERL_CALLCONV char * Perl_sv_collxfrm(pTHX_ SV *const sv, STRLEN *const nxp);
 PERL_CALLCONV bool Perl_sv_2bool(pTHX_ register SV *const sv);
+PERL_CALLCONV void Perl_mro_isa_changed_in(HV* stash);
 
 /* ref() is now a macro using Perl_doref;
  * this version provided for binary compatibility only.
@@ -1554,6 +1555,12 @@ Perl_sv_2bool(pTHX_ register SV *const sv)
     return sv_2bool_flags(sv, SV_GMAGIC);
 }
 
+void
+Perl_mro_isa_changed_in(pTHX_ HV* stash)
+{
+    return mro_isa_changed_in3(stash, NULL, 0);
+}
+
 #endif /* NO_MATHOMS */
 
 /*