common: convert scripts to python

run

@@ -176,7 +176,7 @@ if "$common_gem5"; then
   gem5_common="\
 M5_PATH='${common_gem5_system_dir}' \\
 ${debug_vm}\
-'${common_exec}' \\
+'${common_executable}' \\
 --debug-file=trace.txt \\
 ${gem5opts}\
 -d '${common_m5out_dir}' \\
@@ -248,14 +248,14 @@ else
   fi
   if "$prebuilt"; then
     common_mkdir
-    qemu_exec="qemu-system-${common_arch}"
+    qemu_executable="qemu-system-${common_arch}"
   else
-    qemu_exec="${common_qemu_exec}"
+    qemu_executable="${common_qemu_exec}"
   fi
   extra_flags="${extra_flags_qemu}${extra_flags}"
   qemu_common="\
 ${debug_vm}\
-${qemu_exec} \\
+${qemu_executable} \\
 -device rtl8139,netdev=net0 \\
 -gdb 'tcp::${common_gdb_port}' \\
 -kernel '${common_linux_image}' \\