Some tests, such as those under LibGL, try to load shared libraries at
runtime which are stored in Build/lagom. Because all tests' working
directory is that of their CMakeLists.txt file, they fail to find those
shared libraries at runtime.
Set LD_LIBRARY_PATH to Build/lagom so the tests may find the shared
libraries. This fixes, for example, both of these commands:
./Meta/serenity.sh test lagom TestAPI
./Meta/serenity.sh run lagom TestAPI