Minor fix in GraalVM launchers

Author: steve-s

com.oracle.truffle.r.release/src/R_legacy

@@ -82,7 +82,7 @@ for o in "$@"; do
             done
         fi
     elif [[ "$o" == --vm.* ]]; then
-        vm_arg=("${o#--vm.}")
+        vm_arg="${o#--vm.}"
         if [[ "$vm_arg" == "cp" ]]; then
             >&2 echo "'--vm.cp' argument must be of the form '--vm.cp=<classpath>', not two separate arguments"
             exit 1

com.oracle.truffle.r.release/src/Rscript_legacy

@@ -82,7 +82,7 @@ for o in "$@"; do
             done
         fi
     elif [[ "$o" == --vm.* ]]; then
-        vm_arg=("${o#--vm.}")
+        vm_arg="${o#--vm.}"
         if [[ "$vm_arg" == "cp" ]]; then
             >&2 echo "'--vm.cp' argument must be of the form '--vm.cp=<classpath>', not two separate arguments"
             exit 1