[BUG] remove --gc-sections from debug cmake variant with new toolchain file

[DanAlbert]

Description

https://github.com/android/ndk/issues/1813 wasn't able to be fixed for the new toolchain file because CMake doesn't offer us that level of control. We need to get CMake fixed to allow us to fix this for that configuration.

Affected versions

r25, Canary

Canary version

No response

Host OS

Linux, Mac, Windows

Host OS version

any

Affected ABIs

armeabi-v7a, arm64-v8a, x86, x86_64

Build system

CMake

Other build system

No response

minSdkVersion

any

Device API level

No response

[rpavlik]

Can this be done with generator expressions? $<IF:$<CONFIG:Debug>,,--gc-sections> or something like that should add the flag only when it's not in debug mode. I'm not 100% sure it works when put in the toolchain file level variables, but maybe...