basic: add a size check to format timex members properly

As of glibc-2.34, the size of members in struct timex varies depending on
the _TIME_BITS macro.

Fixes: https://github.com/systemd/systemd/issues/21826

src/basic/format-util.h

@@ -26,10 +26,12 @@ assert_cc(sizeof(gid_t) == sizeof(uint32_t));
 #  error Unknown time_t size
 #endif
 
-#if defined __x86_64__ && defined __ILP32__
+#if SIZEOF_TIMEX_MEMBER == 8
 #  define PRI_TIMEX PRIi64
-#else
+#elif SIZEOF_TIMEX_MEMBER == 4
 #  define PRI_TIMEX "li"
+#else
+#  error Unknown timex member size
 #endif
 
 #if SIZEOF_RLIM_T == 8