Most unit test files checked UNITTEST_FRAMEWORK_LIBRARY_EXIST and
adapted themselves accordingly to either use the header-only version or
link with the library. Alas, eight files didn't so the project couldn't
really be tested with the header-only version of that Boost library.
This patch adds the missing pre-processor logic to the files that were
missing it. The style of using no indentation after the '#' was
followed from the existing unit test files. Some other files in this
repository do indent their pre-processor logic, though.
Since replicating the conditional in every file is kind of verbose,
tedious and, apparently, easily forgotten, I'm wondering whether
isolating that logic into a tiny little auxiliary header and then
unconditionally including that one in each unit test file would be a
good idea, though.
