kconfig: improve error message for dependency between choice members

A choice member must not depend on another member within the same choice
block.

Kconfig detects this, but the error message is not sensible.

[Test Code]

    choice
            prompt "choose"

    config A
            bool "A"
            depends on B

    config B
            bool "B"

    endchoice

[Result]

    Kconfig:1:error: recursive dependency detected!
    Kconfig:1:      choice <choice> contains symbol A
    Kconfig:4:      symbol A is part of choice B
    Kconfig:8:      symbol B is part of choice <choice>
    For a resolution refer to Documentation/kbuild/kconfig-language.rst
    subsection "Kconfig recursive dependency limitations"

The phrase "part of choice B" is weird because B is not a choice block,
but a choice member.

To determine whether the current symbol is a part of a choice block,
sym_is_choice(next_sym) must be checked.

This commit improves the error message to:

    Kconfig:1:error: recursive dependency detected!
    Kconfig:1:      choice <choice> contains symbol A
    Kconfig:4:      symbol A symbol is visible depending on B
    Kconfig:8:      symbol B is part of choice <choice>
    For a resolution refer to Documentation/kbuild/kconfig-language.rst
    subsection "Kconfig recursive dependency limitations"
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/symbol.c

@@ -1111,7 +1111,7 @@ static void sym_check_print_recursive(struct symbol *last_sym)
 				menu->filename, menu->lineno,
 				sym->name ? sym->name : "<choice>",
 				next_sym->name ? next_sym->name : "<choice>");
-		} else if (sym_is_choice_value(sym)) {
+		} else if (sym_is_choice(next_sym)) {
 			fprintf(stderr, "%s:%d:\tsymbol %s is part of choice %s\n",
 				menu->filename, menu->lineno,
 				sym->name ? sym->name : "<choice>",