cmake: use GSL_INCLUDE_DIRS
cmake: use GSL_INCLUDE_DIRS

electronic-structure/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,electronic-structure/sirius,toxa81/sirius,electronic-structure/sirius,toxa81/sirius,electronic-structure/sirius,electronic-structure/sirius,toxa81/sirius,toxa81/sirius,toxa81/sirius