[CMake] target_include_directories called with invalid arguments

[Michael Hennebry]

What is the matter with the second line?
target_link_libraries(bootloader-atmega2560.elf egad)
target_include_directories(bootloader-atmega2560.elf .)

Cmake likes the first, spits out the second.
The commands have the same requirements for the first argument.
How could "." (dot) possibly be an invalid include directory?

I've tried other directories,
but dot seems to be the one with the least excuse for rejection.