isl_map_coalesce: fix some regressions introduced by recent extensions
isl_map_coalesce: fix some regressions introduced by recent extensions

c4dc489 (isl_map_coalesce: handle more cases) extended the possibilities
for fusing two basic maps, but introduced some regressions.
Specifically, a "continue" was missing and the code for copying
integer division definitions was removed by mistake.

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