Update PlatformIO build to use new platform

[maxgerhardt]

• Removed add_nanolib.py and referenced to it because it handled in the platform's builder code as default
• changed platform to the new platform-gd32, do not piggy-back on ststm32 anymore
• add reference to bleeding-edge new SPL package
• replaced the old board = gd32f130c6 with the new board = genericGD32F130C6 built-in board name, as per https://github.com/CommunityGD32Cores/platform-gd32/tree/main/boards
• remove old boards/ folder as that is in the platform now
• Removed setting -DGD32F130_150 because the board definition file already does that
• Removed setting -lc -lm because those are already linked automatically
• Removed setting linker-script via old -T./GD32F130C6T_FLASH.ld style, replaced by referencing it as board_build.ldscript, as documented and supported by the build script

All firmwares still build, the DEBUG variant is however very close to having its flash filled up

RAM:   [=         ]  14.9% (used 612 bytes from 4096 bytes)
Flash: [==========]  98.8% (used 32364 bytes from 32768 bytes)

Environment         Status    Duration
------------------  --------  ------------
VARIANT_DEBUG       SUCCESS   00:00:03.148
VARIANT_HOVERCAR    SUCCESS   00:00:03.149
VARIANT_HOVERBOARD  SUCCESS   00:00:02.165

[maxgerhardt]

I've also checked to see whether the Makefile build path uses the same SPL version as we do and it does, V3.1.0,

https://github.com/CommunityGD32Cores/gd32-pio-spl-package/blob/67a6fe90b20e00b11a9a52f55d318b7d15eeed84/gd32/spl/variants/gd32f1x0/inc/gd32f1x0_adc.h#L9-L13

https://github.com/EmanuelFeru/hoverboard-sideboard-hack-GD/blob/1842991849854dd365733cbb69f1a1ec893cceee/Drivers/GD32F1x0_standard_peripheral/Include/gd32f1x0_adc.h#L9-L13

but we're probably going to update to V3.3.2 (https://github.com/CommunityGD32Cores/gigadevice-firmware-and-docs/tree/main/GD32F1x0) soon, and that would mean that the PIO & Makefile builds would use different SPL versions. You can modify

platform_packages = 
    framework-spl-gd32@https://github.com/CommunityGD32Cores/gd32-pio-spl-package.git

to

platform_packages = 
    framework-spl-gd32@https://github.com/CommunityGD32Cores/gd32-pio-spl-package.git#67a6fe90b20e00b11a9a52f55d318b7d15eeed84

to fix it to a known a commit with V3.1.0, or I can ping you when we release an update so you can recheck and update the Makefile path files (Drivers/ etc).

[EFeru]

This looks very good! I am doing a quick check on my computer.

[EFeru]

Perfect. Merge done!