getdeps: improve how run_cmake.py invokes ctest
getdeps: improve how run_cmake.py invokes ctest

Summary:
Update the generated `run_cmake.py` script to tell ctest to print the test
output on failure.  Also pass in a `-j` flag to run tests in parallel by
default.

These flags are already passed in by default when running `getdeps.py test`;
this simply updates this developer utility script to do the same.

Reviewed By: wez

Differential Revision: D21307806

fbshipit-source-id: 42045b0f9362494042c79bc946a1004ff8ad98b6

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