CPack/STGZ: Require explicit acceptance or refusal of license

To make using the generated STGZ easier, require a specific answer to
accepting the license terms.  Since more moves down one line when '\n'
is entered a user may hold enter to paginate through the document. This
change prevents the user from accidentally refusing the license terms by
holding enter for too long and having to start over.

Modules/Internal/CPack/CPack.STGZ_Header.sh.in

@@ -86,15 +86,19 @@ then
 @CPACK_RESOURCE_FILE_LICENSE_CONTENT@
 ____cpack__here_doc____
     echo
-    echo "Do you accept the license? [yN]: "
-    read line leftover
-    case ${line} in
-      y* | Y*)
-        cpack_license_accepted=TRUE;;
-      *)
-        echo "License not accepted. Exiting ..."
-        exit 1;;
-    esac
+    while true
+      do
+        echo "Do you accept the license? [yn]: "
+        read line leftover
+        case ${line} in
+          y* | Y*)
+            cpack_license_accepted=TRUE
+            break;;
+          n* | N* | q* | Q* | e* | E*)
+            echo "License not accepted. Exiting ..."
+            exit 1;;
+        esac
+      done
   fi
 
   if [ "x${cpack_include_subdir}x" = "xx" ]