sys/term/readkey: bugfix: make -t and -E work together
sys/term/readkey: bugfix: make -t and -E work together

libexec/modernish/sys/term/readkey.mm:
- If a timeout (-t) and regular expression (-E) were specified
  together, and the timeout expired, the resulting empty string
  would not match the regular expression and readkey would loop
  instead of exit as expected. Fix this by checking for empty
  input.

modernish/modernish