kconfig: add named choice group

As choice dependency are now fully checked, it's quite easy to add support
for named choices. This lifts the restriction that a choice value can only
appear once, although it still has to be within the same group,
but multiple choices can be joined by giving them a name.
While at it I cleaned up a little the choice type logic to simplify it a
bit.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/kconfig/zconf.y b/scripts/kconfig/zconf.y
index d9b96ba..9710b82 100644
--- a/scripts/kconfig/zconf.y
+++ b/scripts/kconfig/zconf.y
@@ -91,7 +91,7 @@
 %type <id> end
 %type <id> option_name
 %type <menu> if_entry menu_entry choice_entry
-%type <string> symbol_option_arg
+%type <string> symbol_option_arg word_opt
 
 %destructor {
 	fprintf(stderr, "%s:%d: missing end statement for this entry\n",
@@ -239,10 +239,10 @@
 
 /* choice entry */
 
-choice: T_CHOICE T_EOL
+choice: T_CHOICE word_opt T_EOL
 {
-	struct symbol *sym = sym_lookup(NULL, 0);
-	sym->flags |= SYMBOL_CHOICE;
+	struct symbol *sym = sym_lookup($2, SYMBOL_CHOICE);
+	sym->flags |= SYMBOL_AUTO;
 	menu_add_entry(sym);
 	menu_add_expr(P_CHOICE, NULL, NULL);
 	printd(DEBUG_PARSE, "%s:%d:choice\n", zconf_curname(), zconf_lineno());
@@ -456,9 +456,12 @@
 ;
 
 symbol:	  T_WORD	{ $$ = sym_lookup($1, 0); free($1); }
-	| T_WORD_QUOTE	{ $$ = sym_lookup($1, 1); free($1); }
+	| T_WORD_QUOTE	{ $$ = sym_lookup($1, SYMBOL_CONST); free($1); }
 ;
 
+word_opt: /* empty */			{ $$ = NULL; }
+	| T_WORD
+
 %%
 
 void conf_parse(const char *name)