No, addoldvers is never true. S_init_perllib has many calls to incpush like

#ifdef PERL_VENDORLIB_EXP
#  if defined(WIN32)
    /* this picks up vendorarch as well */
    s = win32_get_vendorlib(PERL_FS_VERSION, &len);
    if (s)
        incpush_use_sep(s, len, INCPUSH_ADD_SUB_DIRS|INCPUSH_CAN_RELOC
+ATE);
#  else
    S_incpush_use_sep(aTHX_ STR_WITH_LEN(PERL_VENDORLIB_EXP),
              INCPUSH_CAN_RELOCATE);
#  endif
#endif
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For some reason addoldvers is never true.

update: This is my latest try, it didn't work

perl -pi.orig -e " s!^d_inc_version_list=.*$!d_inc_version_list='defin
+e'! " win32/config.gc
perl -pi.orig -e " s!^inc_version_list=.*$!inc_version_list='5.10.1 5.
+10.0'! " win32/config.gc
perl -pi.orig -e " s!^inc_version_list_init=.*$!inc_version_list_init=
+'\x225.10.1\x22, \x225.10.0\x22, 0'! " win32/config.gc

perl -pi.orig -e " s!^.*#define PERL_INC_VERSION_LIST.*$!#define PERL_
+INC_VERSION_LIST \x225.10.1\x22, \x225.10.0\x22, 0! " win32/config_H.
+gc



perl -pi.orig -e " s!^#INST_VER!INST_VER! " win32/makefile.mk
perl -pi.orig -e " s!^#INST_ARCH!INST_ARCH! " win32/makefile.mk
perl -pi.orig -e " s!^#USE_SITECUST!USE_SITECUST! " win32/makefile.mk

perl -pi.orig -e " s!^(LIBC\s+=\s+-lmsvcrt)!#$1! " win32/makefile.mk


@rem @echo for 5.11.x
perl -pi.orig -e " !/#define/ and !/INCPUSH_ADD_OLD_VERS/ and s!INCPUS
+H_CAN_RELOCATE!INCPUSH_CAN_RELOCATE|INCPUSH_ADD_OLD_VERS ! " perl.c 
@rem @echo for 5.10.x
perl -pi.orig -e " !/#define/ and s!incpush\(\s*(\w+)\s*,\s*(TRUE|FALS
+E)\s*,\s*(TRUE|FALSE)\s*,\s*(TRUE|FALSE)\s*,\s*(TRUE|FALSE)\s*\);!inc
+push($1,$2,$3,TRUE,$4);! " perl.c 




del *.orig
del win32\*.orig


cd win32 
dmake -f makefile.mk install
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