lib: cbprintf: work around LLVM code generation bug

LLVM building for qemu_x86 appears to have an optimization bug where a
union that is assigned to hold values read from va_args() is inferred
to be a constant value, so is placed in ROM with an all-zero content.

Prevent this by packing the conversion state and the value union into
a single container structure that's stack allocated.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
1 file changed