* maint:
  Fix compiler crash when compiling some receive statements

The compiler would crash when compiling the following code:

    do(Acc) ->
        receive
            {Pid, abc} ->
                ok;
            {Pid, []} ->
                ok;
            {Pid, _Res} ->
                exit(_Res)
        end,
        do([Pid | Acc]).

The last clause that always raises an exception would confuse the
compiler so that it would think that the `receive` statement was at the
end of the function and it would generate incorrect code for the `do/1`
call following the `receive`.

https://bugs.erlang.org/browse/ERL-1022

* john/compiler/fix-bs_skip-succeeded-oddity:
  compiler: Fix awkward match context substitution
  beam_ssa_lint: Use #b_var{} instead of variable names

* john/compiler/remove-dead-code-beam_ssa_type:
  beam_ssa_type: Remove unreachable code

Expand and squeeze literal integers/utf8 bin segments

This worked out by accident since codegen never actually looks at
the arguments for 'succeeded'; it just assumes that they reference
the preceding instruction.

Now that impossible branches are skipped altogether, it's no
longer possible to encounter get_tuple_element with a 'none'
argument.

* john/compiler/validator-improve-try_case-handling:
  beam_validator: Disallow jumps to try_case handlers

* john/compiler/explicit-call-exceptions:
  compiler: Simplify set_tuple_element optimization
  compiler: Make 'succeeded' optimization more general
  compiler: Simplify call type optimization
  compiler: All calls may throw, so they all need success checks
  erts_debug: Turn off unsafe optimizations in test case