* in Configure, this is the way to force them into availability.
*
* BOOTSTRAP_CHARSET
+ * DOUBLEKIND
* HAS_ACOSH
* HAS_ASCTIME64
* HAS_CTIME64
* HAS_DLADDR
* HAS_FEGETROUND
* HAS_FPCLASSIFY
+ * HAS_FREELOCALE
* HAS_GMTIME64
* HAS_ISFINITEL
* HAS_ISINFL
+ * HAS_ISLESS
* HAS_J0
* HAS_LOCALTIME64
+ * HAS_MEMMEM
* HAS_MKTIME64
+ * HAS_NEWLOCALE
* HAS_PRCTL
* HAS_PSEUDOFORK
* HAS_TIMEGM
+ * HAS_USELOCALE
* I16SIZE
* I64SIZE
* I8SIZE
* LOCALTIME_R_NEEDS_TZSET
+ * LONG_DOUBLEKIND
* U8SIZE
* USE_CBACKTRACE
*/