string-buffer tests: Avoid test failure on native Windows

[Bruno Haible]

Michele Locati wrote:
> I tried checking gnulib in a similar environment [4], and there we
> have these failures:
> ...
> FAIL: test-string-buffer
> ========================
> ../../gltests/test-string-buffer.c:159: assertion 'ret < 0' failed
> FAIL test-string-buffer.exe (exit status: 3)

Fixed as follows. Thanks for the report.


2024-09-26  Bruno Haible  <br...@clisp.org>

        string-buffer tests: Avoid test failure on native Windows.
        Reported by Michele Locati <mloc...@gmail.com> in
        <https://lists.gnu.org/archive/html/bug-gnulib/2024-09/msg00135.html>.
        * tests/test-string-buffer.c (main): Skip a wchar_t test on native
        Windows.

diff --git a/tests/test-string-buffer.c b/tests/test-string-buffer.c
index 580263b656..2bbb47cff2 100644
--- a/tests/test-string-buffer.c
+++ b/tests/test-string-buffer.c
@@ -155,7 +155,7 @@ main ()
     sb_append_c (&buffer, "<");
 
     ret = sb_appendf (&buffer, "%lc", (wint_t) 0x76543210);
-    #if !defined _AIX
+    #if !(defined _AIX || (defined _WIN32 && !defined __CYGWIN__))
     ASSERT (ret < 0);
     ASSERT (errno == EILSEQ);
     #endif