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[Target] Do not skip a stop on a breakpoint if a plan was completed

Description

[Target] Do not skip a stop on a breakpoint if a plan was completed

Summary:
This patch fixes the next situation. On Windows clang-cl makes no stub before
the main function, so the main function is located exactly on module entry
point. May be it is the same on other platforms. So consider the following
sequence:

  • set a breakpoint on main and stop there;
  • try to evaluate expression, which requires a code execution on the debuggee side. Such an execution always returns to the module entry, and the plan waits for it there;
  • the plan understands that it is complete now and removes its breakpoint. But the breakpoint site is still there, because we also have a breakpoint on entry;
  • StopInfo analyzes a situation. It sees that we have stopped on the breakpoint site, and it sees that the breakpoint site has owners, and no one logical breakpoint is internal (because the plan is already completed and it have removed its breakpoint);
  • StopInfo thinks that it's a user breakpoint and skips it to avoid recursive computations;
  • the program continues.

So in this situation the program continues without a stop right after
the expression evaluation. To avoid this an additional check that
the plan was completed was added.

Reviewers: jingham, zturner, boris.ulasevich

Reviewed by: jingham

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D53761