error: Use error_report_err() instead of monitor_printf()

error: Use error_report_err() instead of monitor_printf()

Both error_report_err() and monitor_printf() print to the same
destination when monitor_printf() is used correctly, i.e. within an
HMP monitor.  Elsewhere, monitor_printf() does nothing, while
error_report_err() reports to stderr.

Most changed functions are HMP command handlers.  These should only
run within an HMP monitor.  The one exception is bdrv_password_cb(),
which should also only run within an HMP monitor.

Four command handlers prefix the error message with the command name:
balloon, migrate_set_capability, migrate_set_parameter, migrate.
Pointless, drop.

Unlike monitor_printf(), error_report_err() uses the error whole
instead of just its message obtained with error_get_pretty().  This
avoids suppressing its hint (see commit 50b7b00).  Example:

    (qemu) device_add ivshmem,id=666
    Parameter 'id' expects an identifier
    Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.
    Try "help device_add" for more information

The "Identifiers consist of..." line is new with this patch.

Coccinelle semantic patch:

    @@
    expression M, E;
    @@
    -    monitor_printf(M, "%s\n", error_get_pretty(E));
    -    error_free(E);
    +    error_report_err(E);
    @r1@
    expression M, E;
    format F;
    position p;
    @@
    -    monitor_printf(M, "...%@F@\n", error_get_pretty(E));@p
    -    error_free(E);
    +    error_report_err(E);
    @script:python@
	p << r1.p;
    @@
    print "%s:%s:%s: prefix dropped" % (p[0].file, p[0].line, p[0].column)

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1450452927-8346-4-git-send-email-armbru@redhat.com>