xml BUGFIX heap oob crash issues in lyxml_parse_value (#1129)
xml BUGFIX heap oob crash issues in lyxml_parse_value (#1129)

Fix an out of bounds write that appeared due to buf being increased in size
only once, even if len + offset + 4 were larger than size by a number
larger than BUFSIZE_STEP. Incrementally increase the buffer size, as long as it
is smaller than len + offset + 4.

Fix uninitialized variable u used to store a UTF-8 character in the same
function to stop valgrind complains about uninitialized reads.
sartura/libyang,sartura/libyang,CESNET/libyang,CESNET/libyang,sartura/libyang,sartura/libyang,sartura/libyang,sartura/libyang