Updated p5-libwww to 6.18.

6.18 2017-02-02
    - Update "timeout" when reusing sockets (PR#90)
    - Fix bug triggered when calling simple_request() with a malformed URL
      (PR#108)

6.17 2017-01-31
- Noted another protocol failure message (PR#65)
- Removed old use of UNIVERSAL::isa() and swapped evals for Try::Tiny (PR#105)
- Standardized the Changes file (GH#106)
- Fixed documentation error in lwp-request.

(wiz)