isl_map.c: parameter_compute_divs: check result of isl_basic_set_gauss call
isl_map.c: parameter_compute_divs: check result of isl_basic_set_gauss call

The return value has been completely ignored ever since the call
was introduced in 2bc8301 (isl_pip_basic_map_compute_divs: remove some
equalities first, Mon May 25 12:59:23 2009 +0200).  This may be harmless
in practice at the moment, but it may lead to future bugs.

Signed-off-by: Sven Verdoolaege <e5350bbed4977f5eb8ae1dc6abd9ae59d21ace75@kotnet.org>

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