Remove getEngine() function from random service

[wddgit]

In the random number generator service, remove the
getEngine function which takes no arguments. This function
is replaced by new getEngine functions that take either
a StreamID or a LuminosityBlockIndex as an argument. This
comes after a long migration of all clients to the new
interface. The new interace is designed to work with
the multithreaded Framework.

(Note that this also fixes a compilation error that resulted
after a similar pull request was automatically merged from
7_1_X)

[cmsbuild]

A new Pull Request was created by @wddgit (W. David Dagenhart) for CMSSW_7_1_THREADED_X.

Remove getEngine() function from random service

It involves the following packages:

FWCore/Utilities
IOMC/RandomEngine

@cmsbuild, @Degano, @Dr15Jones, @ktf, @nclopezo can you please review it and eventually sign? Thanks.
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[wddgit]

I did not do a 'checkdeps -a' test with this to try to get it out faster. I'm assuming the jenkins test will take care of that. Without this the THREADED branch already fails compilation because of a problem in a recent automatic merge from 7_1_X.

[Dr15Jones]

+1
@ktf this needs to be picked up to fix the 0200 build for _THREADED

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_1_THREADED_X IBs unless changes or unless it breaks tests.