Per WiFi library requirement, SSID can be non-null terminated string
if its length goes to 32 bytes (maximum). Use of strncpy in this case,
along with compiler optimization level -O2 results in some warnings
for potential use of non-null terminated strings.
Fix here ensures use of memcpy to copy SSID string upto appropriate
desired length. This helps to avoid compiler specific workaround
flags added earlier.
Closes https://github.com/espressif/esp-idf/issues/5866
Closes IDFGH-3983
xiehang