avutil/dict: Improve appending values

When appending two values (due to AV_DICT_APPEND), the earlier code
would first zero-allocate a buffer of the required size and then
copy both parts into it via av_strlcat(). This is problematic,
as it leads to quadratic performance in case of frequent enlargements.
Fix this by using av_realloc() (which is hopefully designed to handle
such cases in a better way than simply throwing the buffer we already
have away) and by copying the string via memcpy() (after all, we already
calculated the strlen of both strings).

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

0 files changed, 0 insertions, 0 deletions