+/* On AIX, sig_atomic_t already includes volatile. C99 requires that
+ 'volatile sig_atomic_t' ignore the extra modifier, but C89 did not.
+ Hence, redefine this to a non-volatile type as needed. */
+#if ! @HAVE_TYPE_VOLATILE_SIG_ATOMIC_T@
+typedef int rpl_sig_atomic_t;
+# undef sig_atomic_t
+# define sig_atomic_t rpl_sig_atomic_t
+#endif
+