ParseXS: fix POD on last line

If POD continued to the last line of the XS file, a bunch of
"Use of uninitialized value" warnings would be generated.

The fix is trivial, but it also required a slight tweak to the test
framework in t/001-basic.t, which was unconditionally adding a \n to the
end of each test string, thus making the '=cut' appear not to be at EOF.

Author: iabyn

dist/ExtUtils-ParseXS/lib/ExtUtils/ParseXS.pm

@@ -626,6 +626,7 @@ sub fetch_para {
       $self->death("Error: Unterminated pod")
         unless defined $self->{lastline};
       $self->{lastline} = readline($self->{in_fh});
+      return 0 unless defined $self->{lastline};
       chomp $self->{lastline};
       $self->{lastline} =~ s/^\s+$//;
     }

dist/ExtUtils-ParseXS/t/001-basic.t

@@ -87,7 +87,10 @@ sub test_many {
         my ($desc_prefix, $xsub_lines, @tests) = @$test_fn;
 
         my $text = $preamble;
-        $text .= "$_\n" for @$xsub_lines;
+        for (@$xsub_lines) {
+            $text .= $_;
+            $text .= "\n" unless /\n\z/;
+        }
 
         tie *FH, 'Capture';
         my $pxs = ExtUtils::ParseXS->new;
@@ -5795,4 +5798,32 @@ EOF
     test_many($preamble, undef, \@test_fns);
 }
 
+
+{
+    # Test POD
+
+    my $preamble = Q(<<'EOF');
+        |MODULE = Foo PACKAGE = Foo
+        |
+        |PROTOTYPES:  DISABLE
+        |
+EOF
+
+    my @test_fns = (
+        [
+            "POD at EOF doesn't warn",
+            [ Q(<<'EOF') ],
+                |void foo()
+                |
+                |=pod
+                |=cut
+EOF
+
+            [ 0, 0, qr{XS}, "no undef warning" ],
+        ],
+    );
+
+    test_many($preamble, undef, \@test_fns);
+}
+
 done_testing;