(re_match_context_t): Add dfa member.

posix/regex_internal.h

@@ -556,6 +556,11 @@ typedef struct
 {
   /* The string object corresponding to the input string.  */
   re_string_t input;
+#if defined _LIBC || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L)
+  re_dfa_t *const dfa;
+#else
+  re_dfa_t *dfa;
+#endif
   /* EFLAGS of the argument of regexec.  */
   int eflags;
   /* Where the matching ends.  */