[BOLT] Invoke terminator

[aaupov]

Split basic blocks by invoke instructions.

Benefits of switching to an explicit representation of EH control flow:

• Stale profile matching: need to construct sink block + add edges to it from exit blocks because an exit block may have an invoke with a LP.
• Dominance analysis is done on per-instruction basis because of LP edges. <- fixing this could reduce time/mem overhead of dominance analysis and its users.
• Function splitting and block reordering: if continuation/fallthrough is large and cold, it could be outlined.

As a follow-up, LP edges should be added to CFG.

FIXME: this breaks compatibility with old profiles.