weechat: add libgcrypt dependency

Fixes Homebrew#15966.
Closes Homebrew#15967.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Formula/weechat.rb

@@ -8,6 +8,7 @@ class Weechat < Formula
   depends_on 'cmake' => :build
   depends_on 'gettext'
   depends_on 'gnutls'
+  depends_on 'libgcrypt'
   depends_on 'guile'  => :optional if build.include? 'guile'
   depends_on 'aspell' => :optional if build.include? 'aspell'
   depends_on 'lua'    => :optional if build.include? 'lua'