[ELF][Reader] Remove static ordinal.
[ELF][Reader] Refactor how relocations are read. Improves performance.

This changes from reading each relocation individually for each section to just
storing the range of relocations. It also counts the relocations to preallocate
the _references array.
[ELF][Reader][Perf] Only do loookup once.
[ELF][Reader] Add debug message to print all inputs the linker actually read.