Some unit tests don't compile

[thk123]

The following files in unit either don't compile or don't run. They should be fixed and ideally converted into using the Catch framework:

• cpp_parser.cpp
• cpp_scanner.cpp
• elf_reader.cpp
• float_utils.cpp
• ieee_float.cpp
• json.cpp
• osx_fat_reader.cpp
• smt2_parser.cpp
• wp.cpp

[thk123]

unicode.cpp fails on Mac and Windows so was also excluded.