When pjsip_parse_uri is called with PJSIP_UNESCAPE_IN_PLACE enabled,
the input uri string will become corrupted if it contains escape sequences.
It's not possible to automatically strdup or strdupa the input string because
the output uri pj_str_t's will have pointers to chunks of the input string.
Getting around this would require more memory management code and wouldn't
be worth the savings of doing the unescape in place.

ASTERISK-25970 #close
Reported-by: Dmitriy Serov

Change-Id: I28dc0e599b5108f7959b9c46dc8278371b372f88