Add explicit ophd target when building on CircleCI

This isn't really needed. It mostly just makes the code look more symmetric. It also maybe serves as a bit of documentation as to what exactly is being built by that step.

.circleci/config.yml

@@ -8,7 +8,7 @@ commands:
   build:
     steps:
       - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror" nas2d
-      - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror"
+      - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror" ophd
       - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror" testLibOPHD
       - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror" testLibControls
       - run: make --keep-going --jobs 16 CXXFLAGS_EXTRA="-Werror" checkOPHD