errors if minicoredumper elfclass != application elfclass

[jogness]

If a 32-bit application core dumps on a system running a 64-bit minicoredumper, the core dump is incomplete/broken. This comes from the use of the ElfW() macro in corestripper.c. Rather than using this macro, the elfclass should be checked and the appropriate Elf32_ and Elf64_ types used.

This change is not necessarily trivial as the structs "r_debug" and "link_map" also make use of ElfW() in their fields.

• (Imported from Bug 1364 of old Bugzilla tracker.)