add new autodie test file to 'TEST -deparse' skips

autodie tests generally fail the 'deparse and run the test file'
round trip due to stringified references in %^H. Add this newish test
file to the list of excluded test files.

Also add a comment to the file explaining why most autodie tests are
excluded.

Porting/deparse-skips.txt

@@ -94,6 +94,10 @@ uni/tie.t
 uni/universal.t
 uni/variables.t
 ../cpan/Archive-Tar/t/03_file.t         # constant sub ref: FOO->()
+
+# Most autodie tests currently fail under Deparse because
+# the %^H initialisation values are stringifed refs rather
+# than real refs.
 ../cpan/autodie/t/autodie.t
 ../cpan/autodie/t/basic_exceptions.t
 ../cpan/autodie/t/binmode.t
@@ -107,6 +111,7 @@ uni/variables.t
 ../cpan/autodie/t/dbmopen.t
 ../cpan/autodie/t/eval_error.t
 ../cpan/autodie/t/exception_class.t
+../cpan/autodie/t/exception_nonref.t
 ../cpan/autodie/t/exceptions.t
 ../cpan/autodie/t/exec.t
 ../cpan/autodie/t/filehandles.t
@@ -135,6 +140,7 @@ uni/variables.t
 ../cpan/autodie/t/utf8_open.t
 ../cpan/autodie/t/utime.t
 ../cpan/autodie/t/version_tag.t
+
 ../cpan/AutoLoader/t/01AutoLoader.t
 ../cpan/bignum/t/big_e_pi.t
 ../cpan/bignum/t/bigexp.t