irc/weechat: Update to 1.0.1

• Utilise OPTIONS helpers
• Quieten compiler warnings about unused arguments (caused by unconditionally passing LOCALBASE/{lib,includes} via CFLAGS)
• Remove occurrences of deprecated @dirrm and @dirrmtry from plist

Changes: http://www.weechat.org/files/changelog/ChangeLog-1.0.1.html