Don't infinite loop when searching CLI history list

[seanbright]

The easiest way to clean up the history list when moving an item is to
just remove it and reinsert, so use pj_list_erase().

Fixes #2559

[CLAassistant]

All committers have signed the CLA.

[sauwming]

Looking at the spec and implementation of pj_strtrim() doesn't give me assurance that it's safe for zero-length pj_str that has uninitialised ptr.
So perhaps move the strtrim() below the if?

[nanangizz]

The spec does not seem to specify anything about it, but looking at the implementation, the uninitalised ptr should never be dereferenced when the string is zero-length, so it should be safe? Or it is unsafe because of something else?

OTOH the original code seems to assume that the string length is always greater than zero: cmd.slen = pj_ansi_strlen(cmd_val)-1.

It should be better if the string can be trimmed first so we get a 'clean' string when evaluating the length (if (cmd.slen == 0)).

[sauwming]

The code that's bothering me is:
register char *p = end - 1; which, theoretically, when the pj_str is zero length, allows the pointer to be outside the buffer and potentially underflow. Practically, it may be extremely rare, if possible at all, though.

Ah right, you want to check the length after trimming. I initially thought there's no point in doing so and that's why I suggest to move it below.