libwebsockets

struct-lejp: handle no path match

For some patterns of JSON we return to parse at the outermost level and
meet a situation path_match is 0.  In some places we're looking at things
from perspective of path_match - 1... that does not seem to cause trouble on
x86_64 but can on aarch64, which is how it got noticed.

This logically protects those accesses by checking !!path_match.