configure: add --with-polylib-include and --with-polylib-library
configure: add --with-polylib-include and --with-polylib-library

These options are needed for building cloog with the polylib still in
its build directory, or installed in a non standard place.

heysion/cloog-clone,VanirLLVM/toolchain_cloog,VanirLLVM/toolchain_cloog,heysion/cloog-clone,heysion/cloog-clone,cfx-next/toolchain_cloog-upstream,evaautomation/cloog,epowers/cloog,Syllo/cloog,Distrotech/cloog,SaberMod/cloog-current,cfx-next/toolchain_cloog-upstream,VanirLLVM/toolchain_cloog,UBERTC/cloog,UBERTC/cloog,Syllo/cloog,epowers/cloog,periscop/cloog,cfx-next/toolchain_cloog-upstream,UBERTC/cloog,periscop/cloog,epowers/cloog,Distrotech/cloog,Distrotech/cloog,evaautomation/cloog,SaberMod/cloog-current