shell: split read builtin from ash

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

shell/match.h

@@ -1,5 +1,8 @@
 /* match.h - interface to shell ##/%% matching code */
 
+#ifndef SHELL_MATCH_H
+#define SHELL_MATCH_H 1
+
 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
 typedef char *(*scan_t)(char *string, char *match, bool match_at_left);
@@ -24,3 +27,5 @@ static inline scan_t pick_scan(char op1, char op2, bool *match_at_left)
 }
 
 POP_SAVED_FUNCTION_VISIBILITY
+
+#endif