Improve logging of the environment

Show only the variables the care about
Use setenv to ensure that environment variables are unique
Log the command line that is sent to qemu

Test: Local build and boot
BUG: 110962084
Change-Id: I72d049bd1c31f0c9015610110b5444872bd43fcf
diff --git a/host/libs/vm_manager/cf_qemu.sh b/host/libs/vm_manager/cf_qemu.sh
index fa4c872..c93281c 100644
--- a/host/libs/vm_manager/cf_qemu.sh
+++ b/host/libs/vm_manager/cf_qemu.sh
@@ -87,5 +87,14 @@
   args+=(-initrd "${ramdisk_image_path}")
 fi
 
+printf %s "exec ${qemu_binary=/usr/bin/qemu-system-x86_64}"
+for i in "${args[@]}"; do
+  case "$i" in
+    -*) printf "\\%s  %s " $'\n' "$i" ;;
+    *) printf "%s " "$i" ;;
+  esac
+done
+echo
+
 exec "${qemu_binary=/usr/bin/qemu-system-x86_64}" \
   "${args[@]}"