advice: remove read uses of most global `advice_` variables

In c4a09cc9ccb (Merge branch 'hw/advise-ng', 2020-03-25), a new API for
accessing advice variables was introduced and deprecated `advice_config`
in favor of a new array, `advice_setting`.

This patch ports all but two uses which read the status of the global
`advice_` variables over to the new `advice_enabled` API. We'll deal
with advice_add_embedded_repo and advice_graft_file_deprecated
separately.

Signed-off-by: Ben Boeckel <mathstuf@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/am.c b/builtin/am.c
index 0c2ad96..ff7dd33 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1820,7 +1820,7 @@ static void am_run(struct am_state *state, int resume)
 			printf_ln(_("Patch failed at %s %.*s"), msgnum(state),
 				linelen(state->msg), state->msg);
 
-			if (advice_amworkdir)
+			if (advice_enabled(ADVICE_AM_WORK_DIR))
 				advise(_("Use 'git am --show-current-patch=diff' to see the failed patch"));
 
 			die_user_resolve(state);