MIPS: Make elf2ecoff work on 64bit host machines

Use fixed width integer types for ecoff structs to make elf2ecoff work
on 64bit host machines.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19483/


Signed-off-by: Paul Burton <paul.burton@mips.com>