gem5: undo attempt to use the TARGET_CROSS...

gem5/build

@@ -20,15 +20,12 @@ shift "$(($OPTIND - 1))"
 if [ -z "$j" ]; then
   j="$(nproc)"
 fi
-top="$(dirname "$0")"
+top="$(cd $(dirname "$0") && pwd)"
 system_dir="${top}/system"
 binaries_dir="${system_dir}/binaries"
 disks_dir="${system_dir}/disks"
 mkdir -p "$binaries_dir" "$disks_dir"
 cd "${top}/gem5"
-
-TARGET_CROSS=
-
 if [ "$arch" = x86_64 ]; then
   CC=gcc-6 CXX=g++-6 scons -j"$j" --ignore-style build/X86/gem5.opt
   f="${disks_dir}/linux-bigswap2.img"