fix(test): guard the POSIX-only includes in the gitignore test

sys/wait.h does not exist on the Windows toolchain, so the unguarded include
broke the Windows test build outright — the suites never ran. The test body is
already skipped on Windows, so the includes belong behind the same guard, as
test_cypher.c does for the same pair.

Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

tests/test_gitignore.c

@@ -7,8 +7,10 @@
 #include "test_framework.h"
 #include "discover/discover.h"
 #include <string.h> /* strdup (test seam) */
+#ifndef _WIN32
 #include <sys/wait.h> /* fork/waitpid crash-isolation for the backtracking budget */
-#include <unistd.h>
+#include <unistd.h>   /* alarm() as the liveness backstop */
+#endif
 
 /* ── Basic pattern matching ────────────────────────────────────── */