common: simplify set_common_vars, rename to common_setup

Don't pass all arguments explicitly, just use existing vars.

Prefix all common_setup inputs and outputs with common_ to avoid name conflicts.

gem5-stat

@@ -1,10 +1,11 @@
 #!/usr/bin/env bash
 set -eu
 . "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/common"
+common_gem5=true
 while getopts a:hs: OPT; do
   case "$OPT" in
     a)
-      arch="$OPTARG"
+      common_arch="$OPTARG"
       ;;
     h)
       printf "\
@@ -21,5 +22,5 @@ if [ $# -gt 0 ]; then
 else
   stat=system.cpu[0-9]*.numCycles
 fi
-set_common_vars "$arch" true
+common_setup
 awk "/^$stat /{ print \$2 }" "${common_m5out_dir}/stats.txt"