isl_space_check_named_params: change error message
isl_space_check_named_params: change error message

All current uses of isl_space_check_named_params are from within
some isl_*_align_params function, but this will change in the next commit.
Pick a more generic error message.

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,inducer/isl-mirror,PollyLabs/isl,PollyLabs/isl,Meinersbur/isl,Meinersbur/isl,inducer/isl-mirror,Meinersbur/isl,PollyLabs/isl,Meinersbur/isl