[BOLT] Improve Linux Kernel ORC reader

  * Sort ORC entries in the internal table. Older Linux kernels did not
    sort them in the file (only during boot time).
  * Add an option to dump sorted ORC tables (--dump-orc).
  * Associate entries in the internal ORC table with a BinaryFunction
    even when we are not changing the function.
  * If the function doesn't have ORC entry at the start, propagate ORC
    state from a previous entry.

Reviewed By: Amir

Differential Revision: https://reviews.llvm.org/D155767