CTYPE_MASK_blank
/* 09 \t */ CTYPE_MASK_blank | CTYPE_MASK_cntrl | CTYPE_MASK_space,
/* 20 */ CTYPE_MASK_blank | CTYPE_MASK_print | CTYPE_MASK_space
#define ossl_isblank(c) (ossl_ctype_check((c), CTYPE_MASK_blank))