Support MIPS64 .o files - don't remove has_addend (#495)

Support MIPS64 .o files - don't remove has_addend (#495)

* Update relocation.py to support MIPS64 .o files. Add a test file. DWARF test still shows an error.

* Make test pass for test/testfiles_for_readelf/simple_mips_gcc.o.elf by having two _RELOCATION_RECIPES_MIPS, one for REL and one for RELA

* Adjust llvm-dwarfdump output for MIPS64 to match pyelftools and gcc-objdump.

* update dwarf_mips64el.o.elf

* Change dwarf_mips64el.c to not use globals

Now we don't depend on whether relocations on globals in .o should be performed or not.

* run_dwarfdump_test.py: add a comment to explain the special case.

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Co-authored-by: Noam Yorav-Raphael <noam.yoravraphael@mobileye.com>
Co-authored-by: Noam Yorav-Raphael <noamyr@mobileye.com>