gh-149879: Fix test_c_stack_unwind on Cygwin

On Cygwin, the Python library is called "cygpython3.16.dll".

Author: vstinner

Modules/_testinternalcapi.c

@@ -240,10 +240,17 @@ classify_address(uintptr_t addr, int jit_enabled, PyInterpreterState *interp)
         if (strncmp(base, "python", 6) == 0) {
             return "python";
         }
+#ifdef __CYGWIN__
+        // Match Cygwin "cygpython3.16.dll"
+        if (strncmp(base, "cygpython", 9) == 0) {
+            return "python";
+        }
+#else
         // Match "libpython3.15.so.1.0"
         if (strncmp(base, "libpython", 9) == 0) {
             return "python";
         }
+#endif
         return "other";
     }
 #ifdef _Py_JIT