Rely on NoMethodError#name when deciding to raise DelegationError.

Different Ruby implementations present backtraces differently, as
it should be an information consumed by humans.
A better implementation should use data from the error, in this case
returned by NoMethodError#name.

Fixes issues with Rubinius, which presents backtraces differently from
MRI.
Merge pull request #11850 from razielgn/mod-delegation-backtrace

Generalize backtrace check on DelegationError.