This patch also adds sharing of code target entries, which requires
sharing the RelocInfo for those entries as well. The disassembler
is also modified in order to print comments for the RelocInfo that
is now shared.

This improves the snapshot size for arm by about 4%.

BUG=

Review-Url: https://codereview.chromium.org/2869683004
Cr-Commit-Position: refs/heads/master@{#45497}