isl_basic_set_project_out: handle rational sets
isl_basic_set_project_out: handle rational sets

For rational sets, projection boils down to (Fourier-Motzkin)
elimination, so just call isl_basic_set_remove.

UBERTC/isl,VanirLLVM/toolchain_isl,abduld/isl,BobSaget-Mod/libisl,inducer/isl-mirror,nicolasvasilache/isl,inducer/isl-mirror,PollyLabs/isl,simbuerg/isl,cfx-next/toolchain_isl-upstream,simbuerg/isl,serge-sans-paille/isl,Meinersbur/isl,BenzoSM/isl,simbuerg/isl,VanirLLVM/toolchain_isl,BenzoSM/isl,KangDroidSMProject/ISL,SaberMod/isl-current,Meinersbur/isl,KangDroidSMProject/ISL,cfx-next/toolchain_isl-upstream,PollyLabs/isl,UBERTC/isl,nicolasvasilache/isl,SaberMod/isl-current,evaautomation/isl,jleben/isl,Distrotech/isl,PollyLabs/isl,inducer/isl-mirror,BenzoSM/isl,VanirLLVM/toolchain_isl,epowers/isl,pierrotdelalune/isl,evaautomation/isl,abduld/isl,VanirLLVM/toolchain_isl,crossbuild/isl,crossbuild/isl,epowers/isl,tobig/isl,nicolasvasilache/isl,serge-sans-paille/isl,BobSaget-Mod/libisl,BobSaget-Mod/libisl,jleben/isl,tobig/isl,jleben/isl,Distrotech/isl,PollyLabs/isl,simbuerg/isl,tobig/isl,Distrotech/isl,pierrotdelalune/isl,cfx-next/toolchain_isl-upstream,epowers/isl,SaberMod/isl-current,Meinersbur/isl,Meinersbur/isl,VanirLLVM/toolchain_isl,pierrotdelalune/isl,serge-sans-paille/isl,cfx-next/toolchain_isl-upstream,inducer/isl-mirror,epowers/isl,Distrotech/isl,jleben/isl,BenzoSM/isl,UBERTC/isl,SaberMod/isl-current,tobig/isl,pierrotdelalune/isl,PollyLabs/isl,Distrotech/isl,BobSaget-Mod/libisl,UBERTC/isl,evaautomation/isl,KangDroidSMProject/ISL,KangDroidSMProject/ISL,simbuerg/isl,jleben/isl,crossbuild/isl,BenzoSM/isl,serge-sans-paille/isl,abduld/isl,pierrotdelalune/isl,abduld/isl,crossbuild/isl,serge-sans-paille/isl,BobSaget-Mod/libisl,inducer/isl-mirror,evaautomation/isl,KangDroidSMProject/ISL,cfx-next/toolchain_isl-upstream,nicolasvasilache/isl,epowers/isl,nicolasvasilache/isl