The variables are usually placed into an output region located in FLASH
memory when linking, but the variables are not marked `const`, so the
section ends up with `W` writeable section flag:
```bash
❯ arm-zephyr-eabi-readelf --section-headers build/zephyr/zephyr.elf | \
grep -E '(Section Headers:)|( \[Nr\])|(zephyr_dbg_info)'
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[10] zephyr_dbg_info PROGBITS 60012298 01238c 000040 00 WA 0 0 4
```
Set them as const to set the output section to read-only:
```bash
❯ arm-zephyr-eabi-readelf --section-headers build/zephyr/zephyr.elf | \
grep -E '(Section Headers:)|( \[Nr\])|(zephyr_dbg_info)'
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[10] zephyr_dbg_info PROGBITS 60012298 01238c 000040 00 A 0 0 4
```
Signed-off-by: Noah Pendleton <noah.pendleton@gmail.com>
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