Replace RegisterNextWire function calls in src/examples/benchmark

[rainiemi]

The build gives the following errors when MOTION executable building is enabled (e.g., with the MOTION_BUILD_EXE option):

MOTION/src/examples/benchmark/common/benchmark.cpp: In function ‘encrypto::motion::ShareWrapper DummyArithmeticGmwShare(encrypto::motion::PartyPointer&, std::size_t, std::size_t)’:
MOTION/src/examples/benchmark/common/benchmark.cpp:54:21: error: ‘using element_type = class encrypto::motion::Register’ {aka ‘class encrypto::motion::Register’} has no member named ‘RegisterNextWire’; did you mean ‘RegisterWire’?
   54 |   register_pointer->RegisterNextWire(wires[0]);
      |                     ^~~~~~~~~~~~~~~~
      |                     RegisterWire
MOTION/src/examples/benchmark/common/benchmark.cpp: In function ‘encrypto::motion::ShareWrapper DummyBmrShare(encrypto::motion::PartyPointer&, std::size_t, std::size_t)’:
MOTION/src/examples/benchmark/common/benchmark.cpp:73:23: error: ‘using element_type = class encrypto::motion::Register’ {aka ‘class encrypto::motion::Register’} has no member named ‘RegisterNextWire’; did you mean ‘RegisterWire’?
   73 |     register_pointer->RegisterNextWire(bmr_wire);
      |                       ^~~~~~~~~~~~~~~~
      |                       RegisterWire
MOTION/src/examples/benchmark/common/benchmark.cpp: In function ‘encrypto::motion::ShareWrapper DummyBooleanGmwShare(encrypto::motion::PartyPointer&, std::size_t, std::size_t)’:
MOTION/src/examples/benchmark/common/benchmark.cpp:97:23: error: ‘using element_type = class encrypto::motion::Register’ {aka ‘class encrypto::motion::Register’} has no member named ‘RegisterNextWire’; did you mean ‘RegisterWire’?
   97 |     register_pointer->RegisterNextWire(w);
      |                       ^~~~~~~~~~~~~~~~
      |                       RegisterWire

Apparently, RegisterNextWire function was removed at some point but benchmark.cpp was not maintained accordingly. This is probably easy to fix, but better that the person who removed the original function also makes the fix for this.

In addition, I suggest that Travis CI configuration is modified to compile the MOTION example executables so that we can detect similar errors immediately in the future.

[Oleksandr-Tkachenko]

Thanks for figuring that out! If it's easy to fix, we would highly appreciate if you could make a PR - that would be great help.

[rainiemi]

Seems that in the dev branch (which is now the default branch), the whole src/examples/benchmark is deleted solving the problem.

Replacing RegisterNextWire with RegisterWire also seemed to solve the compilation issue (as suggested by the compiler), but I didn't want to make a PR because I have no idea why RegisterNextWire wasn't properly deprecated and I cannot be sure that RegisterWire is functioning similarly. Maybe the whole example was meant to be removed but was forgotten. Anyway, updating (or removing) the master branch is now probably the best "solution".