MultipleChoiceSelection.h: added missing header

[PetrilloAtWork]

GitHub commit.

A header inclusion was missing.

[FNALbuild]

A new Pull Request was created by @PetrilloAtWork (Gianluca Petrillo) for develop.

It involves the following packages:

lardataalg

@LArSoft/level-1-managers, @LArSoft/level-2-managers can you please review it and eventually sign? Thanks.

cms-bot commands are listed here

[FNALbuild]

The code-checks are being triggered in jenkins.

[FNALbuild]

+code-checks

[lgarren]

trigger build

[FNALbuild]

The tests are being triggered in jenkins.

[FNALbuild]

+LArSoft tests OK on slf7 for c14:prof
for details see
https://lar-ci-history.fnal.gov/LarCI/app/view_builds/index?offset=0&builds=lar_ci/21416&builds=
+build

[FNALbuild]

-uboone tests failed on slf7 for e26:prof
for details see
https://lar-ci-history.fnal.gov/LarCI/app/ns:uboone/view_builds/index?offset=0&builds=uboone_ci/10079&builds=
for details of the parent CI build see
https://lar-ci-history.fnal.gov/LarCI/app/view_builds/index?offset=0&builds=lar_ci/21417&builds=

[FNALbuild]

-icarus tests warning, with build warning,, with ignored failure for unit_test,, with ignored warning for build, on slf7 for e26:prof
for details see
https://lar-ci-history.fnal.gov/LarCI/app/ns:icarus/view_builds/index?offset=0&builds=icarus_ci/8876&builds=
for details of the parent CI build see
https://lar-ci-history.fnal.gov/LarCI/app/view_builds/index?offset=0&builds=lar_ci/21417&builds=

[FNALbuild]

-sbnd tests warning, with build warning,, with ignored warning for build, on slf7 for e26:prof
for details see
https://lar-ci-history.fnal.gov/LarCI/app/ns:sbnd/view_builds/index?offset=0&builds=sbnd_ci/13311&builds=
for details of the parent CI build see
https://lar-ci-history.fnal.gov/LarCI/app/view_builds/index?offset=0&builds=lar_ci/21417&builds=

[FNALbuild]

-dune tests tests warning, with build warning,, with ignored warning for build, on slf7 for e26:prof
for details see
https://lar-ci-history.fnal.gov/LarCI/app/ns:dune/view_builds/index?offset=0&builds=dune_ci/16625&builds=
for details of the parent CI build see
https://lar-ci-history.fnal.gov/LarCI/app/view_builds/index?offset=0&builds=lar_ci/21417&builds=

[knoepfel]

approve

[FNALbuild]

This pull request is fully signed and it will be merged to develop and built in the next LArSoft release after it passes the integration tests.