This patch fixes build with GCC 10.3.0, that fails with warning/error:

  '__builtin_strncpy' specified bound depends on the length
  of the source argument [-Werror=stringop-overflow=]

Destination buffer size is is checked properly,
memcpy is equivalent to strncpy here as pointed by Santtu.

This patch replaces my previous one:
"dnsproxy: Suppress GCC warning stringop-overflow"

Lukas