Remove trailing comma from powers output, and don't override the locale

[argilo]

powers prints a trailing comma at the end of each line. Here I have removed the extraneous comma, which makes the output more like rtl_power.

[argilo]

I added a second commit to fix another bug. Namely, powers overrides the C locale, which corrupts the CSV output in locales which use a comma as the decimal point:

argilo@sonde:~ $ LANG=de_DE.UTF-8 powers radiosonde.local -f 403025000.0 -w 800.0 -b 10 -i 1 -s 1234 -c 2
Sat 16 Nov 2024 00:18:39.417195 UTC, 403020992, 403028192, 800, 10, -0,4, -0,4, -0,1, -0,1, -0,4, -0,4, -0,4, -0,4, -0,5, -0,5,
Sat 16 Nov 2024 00:18:40.434490 UTC, 403020992, 403028192, 800, 10, -0,5, -0,2, 0,0, -0,4, -0,8, -0,6, -0,8, -0,6, -0,6, -0,0,
argilo@sonde:~ $ LANG=C powers radiosonde.local -f 403025000.0 -w 800.0 -b 10 -i 1 -s 1234 -c 2
Sat 16 Nov 2024 00:18:43.079096 UTC, 403020992, 403028192, 800, 10, -0.1, -0.1, 0.2, 0.2, -0.1, -0.1, -0.4, -0.3, -0.3, 0.1,
Sat 16 Nov 2024 00:18:44.096287 UTC, 403020992, 403028192, 800, 10, 0.2, -0.0, 0.2, 0.3, -0.3, 0.2, -0.2, -0.2, -0.0, -0.3,

Removing the locale override fixes the issue by ensuring that the program runs using the C locale.

[ka9q]

Thanks!