Revert D65242 "[ELF] More dynamic relocation packing"

This reverts r369488 and r369489. The change broke build bots:

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap-ubsan/builds/14511
http://lab.llvm.org:8011/builders/lld-x86_64-freebsd/builds/34407

llvm-svn: 369497