Add experiment for analyzing debug info

Analyze entropy of debug info to estimates a close upper bound
savings from huffman encoding debug infos.

Also measure how many debug info bytes are dedupable if you exclude
the line number and parameter names.

Sample output:
Debug info bytes 96101012(5.70%)
  DBG_END_SEQUENCE: 6401069(0.38%)
  DBG_ADVANCE_PC: 3709064(0.22%)
  DBG_ADVANCE_LINE: 8620724(0.51%)
  DBG_START_LOCAL: 5244232(0.31%)
  DBG_START_LOCAL_EXTENDED: 1763845(0.10%)
  DBG_END_LOCAL: 1216044(0.07%)
  DBG_RESTART_LOCAL: 565412(0.03%)
  DBG_SET_PROLOGUE bytes 5768714(0.34%)
  DBG_SET_FILE bytes 0(0.00%)
  special: 36310220(2.15%)
Debug info entropy 69199724(4.10%)
Debug info opcode bytes 55613021(3.30%)
Debug info opcode entropy 34792401(2.06%)
Debug info non header bytes 69599324(4.13%)
Debug info deduped non header bytes 52475493(3.11%)

Bug: 77721545
Test: test-art-host
Change-Id: I031322e3b79a1572fcbb9e513ded9708e3b48354