MCJIT-remote: __main should be resolved in child context.

  - Mark tests as XFAIL:cygming in test/ExecutionEngine/MCJIT/remote.
    Rather to suppress them, I'd like to leave them running as XFAIL.
  - Revert r193472. RecordMemoryManager no longer resolves __main on cygming.

There are a couple of issues.

  - X86 Codegen emits "call __main" in @main for targeting cygming.
    It is useless in JIT. FYI, tests are passing when emitting __main is disabled.
  - Current remote JIT does not resolve any symbols in child context.

FIXME: __main should be disabled, or remote JIT should resolve __main.