gawk: update 5.1.1 -> 5.2.1

Place gawkbug into a separate package, as it includes target information
which causes multilib conflicts.

Adjust ptests so they are correctly executed:
- unset LANG before starting
- do not patch /usr/local/bin into /usr/bin; this is not correct

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>