isl_ast_build_private.h: fix typos in comments
isl_ast_build_private.h: fix typos in comments

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

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