update to arm gcc 15.2Rel1

[dhalbert]

-- Fixes #10521

Update to ARM toolchain gcc 15.2Rel1.

Note that we use our own copy of libgcc for SAMD21 builds. The one that comes with the toolchain is compiled with -O2, but using a -Os version saves about 100 bytes. @tannewt extracted it from the Arch arm-none-eabi-gcc package. That package, as of this writing, has not yet been updated to gcc 15; see https://archlinux.org/packages/extra/x86_64/arm-none-eabi-gcc/.

circuitpython/ports/atmel-samd/Makefile

Line 120 in 8d17d0c

LIBS := libs/libgcc-14.2.0-Os-v6-m-nofp.a -lc

While trying this by hand, I saw size improvements except on on nordic, where the size was about 6kB greater, which sounds like some kind of linking problem. I will investigate that after getting everything to build properly.

[bablokb]

I will update the .devcontainer-script once this is merged.

[dhalbert]

I will update the .devcontainer-script once this is merged.

Thanks for the reminder. I forgot to look in . directories besides .github.

[dhalbert]

For the en_US translation:

Board	size change gcc 14 to gcc 15
Trinket M0	-692
Metro M4	-2260
Circuit Playground Express	-960
Grand Central M4	-2124
Pi Pico	-13668
Pi Pico W	-18716
Pi Pico 2	-27648
Feather STM32F405	+6412
Feather nRF52840 (default optimization: -O2 -fno-inline-functions)	+6112
Feather nRF52840 (default optimization: -O2)	+6512
Feather nRF52840 (-Os)	-1776

So it looks like the size difference is not some linking problem, but growth due to changes in the -O2 optimizer. However, we have plenty of flash to absorb that.

A long time ago in #3752 we added -fno-inline-functions to some bulds to save some space. That's probably not necessary for builds with large flash, like nRF52840, and I'll remove it. Also -ggdb3 was being added for some non-debug builds, which wasn't necessary.

[tannewt]

Thank you!