For bare metal ARM & xtensa targets, passing -g will make the ELF file
larger but doesn't change the binary size. However, this means tools like
gdb, addr2line, etc can extract source-level information from the ELF.
Also standardise -ggdb to -g, these produce the exact same ELF file on
arm-none-eabi-gcc and will use DWARF format for all these ports.