Add .non_init RAM

Is it (already) possible to use variables that are not initialised at softreset?
like:
static uint8_t data[16] __attribute__((section(".non_init")));
or

So after a power-On Reset the Variable "counter" is random or zero
the counter is increased by application.

after a softreset the variable "counter" should contain the old value before the softreset

Reason: i have an Application running which does a reset from time to time (i think it happens at BLE transfer) and some values should be hold. and i cant writ them in Filesystem, because i dont know the time of the next softreset.

Start by checking the nRF52 Arduino startup and linker handling for variables in a .non_init section. Verify how softreset and power-on reset treat the section, then confirm that the counter retains its value across softreset while its power-on state is unspecified or zero.

Written by the indexing model from the issue text.