Treat build-time warnings as errors

[puddly]

Enables -Wall -Wextra -Werror and fixes a few warnings and bugs with compilation.

There is a persistent warning with the PTI interface that can only be fixed if PTI is re-enabled verbosely in every config. I think this is a bug, as this component cannot be excluded:

// <<< sl:start pin_tool >>>
// <pti signal=DOUT,(DFRAME),(DCLK)> SL_RAIL_UTIL_PTI
// $[PTI_SL_RAIL_UTIL_PTI]
#ifndef SL_RAIL_UTIL_PTI_PERIPHERAL             
#warning "RAIL PTI peripheral not configured"
#define SL_RAIL_UTIL_PTI_PERIPHERAL              PTI
#endif

Until this is fixed in the Gecko SDK, this warning is explicitly disabled.

[agners]

Nice! 👍

[puddly]

Looks like there may be some SLC-CLI flakiness. Happened only a single time so far so I'll deal with it if it happens again.