.. see GNU make for more information about this extension, which
prevents unwanted behavior if a file with a name like 'clean' or 'all'
is created accidentally
POSIX printf(1) doesn't support the \xXX specifier to print
characters by their hexadecimal values. By contrast, printing
octal values is portable.
Reference: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html
Signed-off-by: Jeff Epler <jepler@unpythonic.net>
