In commit v3.3.0-rc1~352^2~3 (Genex: Allow COMPILE_LANGUAGE when
processing compile definitions, 2015-03-04) the name of the variable
used to pass preprocessor definitions to the Fortran dependency scanner
was changed to be per-language, but the actual dependency scanning code
was not updated accordingly. Update the code and add a test case.
Reported-by: Radovan Bast <radovan.bast@gmail.com>