disable tests for polyglot as it is failing on OSX
disable tests for polyglot as it is failing on OSX

```
$ ./test/test.native test Simple 0
Testing polyglot.
[ERROR]             Simple           0   no_dtd.
[SKIP]              Simple           1   keep_dtd.
[SKIP]              Simple           2   void.
[SKIP]              Simple           3   nonvoid.
[SKIP]              Simple           4   fragment.
[SKIP]              Simple           5   other_ns.
[SKIP]              Detect           0   detect_no_dtd.
[SKIP]              Detect           1   detect_fragment.
[SKIP]              Detect           2   detect_nonstandard_html.
[SKIP]              Detect           3   detect_no_dtd_xml.
[SKIP]              Detect           4   detect_dtd_xml.
[SKIP]              Error            0   empty.
[SKIP]              Error            1   bad_xml_no_close.
[SKIP]              Error            2   bad_xml_no_open.
-- Simple.000 Failed --
no_dtd.
_build/_tests/Simple.000.output:
[exception] Unix.Unix_error(Unix.ENOENT, "chdir", "no_dtd")
Raised by primitive operation at file "test.ml", line 45, characters 4-18
Re-raised at file "test.ml", line 51, characters 4-11
Called from file "test.ml", line 56, characters 17-93
Called from file "test.ml" (inlined), line 68, characters 17-55
Called from file "test.ml", line 70, characters 31-43
Called from file "src/alcotest.ml", line 268, characters 8-12
```

Chris00/opam-repository,avsm/opam-repository,def-lkb/opam-repository,jhwoodyatt/opam-repository,toots/opam-repository,fpottier/opam-repository,olgu/opam-repository,planar/opam-repository,c-cube/opam-repository,djs55/opam-repository,edwintorok/opam-repository,hakuch/opam-repository,talex5/opam-repository,nberth/opam-repository,orbitz/opam-repository,Chris00/opam-repository,seliopou/opam-repository,kkirstein/opam-repository,astrada/opam-repository,camlspotter/opam-repository,ocaml/opam-repository,hannesm/opam-repository,jhwoodyatt/opam-repository,codinuum/opam-repository,ocaml/opam-repository,jonludlam/opam-repository,pqwy/opam-repository,gdelaval/opam-repository,pirbo/opam-repository,arlencox/opam-repository,fxfactorial/opam-repository,Leonidas-from-XIV/opam-repository,gasche/opam-repository,abate/opam-repository,nberth/opam-repository,pirbo/opam-repository,whitequark/opam-repository,dbuenzli/opam-repository,andersfugmann/opam-repository,seliopou/opam-repository,hannesm/opam-repository,mjambon/opam-repository,djs55/opam-repository,thizanne/opam-repository,dra27/opam-repository,lefessan/opam-repository,andersfugmann/opam-repository,gfxmonk/opam-repository,codinuum/opam-repository,avsm/opam-repository,pqwy/opam-repository,samoht/opam-repository,vprevosto/opam-repository,kkirstein/opam-repository,AltGr/opam-repository,jonludlam/opam-repository,hhugo/opam-repository,cakeplus/opam-repository,camlspotter/opam-repository,talex5/opam-repository,Leonidas-from-XIV/opam-repository,toots/opam-repository,UnixJunkie/opam-repository,lefessan/opam-repository,mjambon/opam-repository,AltGr/opam-repository,c-cube/opam-repository,dsheets/opam-repository,yallop/opam-repository,dra27/opam-repository,rizo/opam-repository,emillon/opam-repository,dbuenzli/opam-repository,emillon/opam-repository,mebsout/opam-repository,yallop/opam-repository,fpottier/opam-repository,astrada/opam-repository