Update check_os.sh (#2469)

On my RHEL system, ID is initially set to  'ID_LIKE="RHEL CENTOS FEDORA"', which, when expanded in the if-statement, turns into  this:
if [ -z ID_LIKE=RHEL CENTOS FEDORA ]; then and causes the error:
`souffle/sh/check_os.sh: line 15: [: too many arguments`

It is necessary to quote $ID

Author: strRM

sh/check_os.sh

@@ -11,7 +11,7 @@ fi
 ID=$(grep -G "^ID_LIKE=" $file | tr a-z A-Z)
 
 #Fedora is special and has no ID_LIKE
-if [ -z $ID ]; then
+if [ -z "$ID" ]; then
     ID=$(grep -G "^ID=" $file | tr a-z A-Z)
 fi