gnu packages: Avoid description lines with leading "(".

gnu packages: Avoid description lines with leading "(".

* gnu/packages/curl.scm (curl): Reformat description to avoid a line
  beginning with "(" because such lines break font-lock highlighting
  in Emacs.
* gnu/packages/flashing-tools.scm (dfu-programmer): Likewise.
* gnu/packages/games.scm (gnugo): Likewise.
* gnu/packages/gnome.scm (json-glib): Likewise.
* gnu/packages/image.scm (jbig2dec): Likewise.
* gnu/packages/maths.scm (units): Likewise.
* gnu/packages/pdf.scm (mupdf): Likewise.
* gnu/packages/web.scm (perl-encode-locale): Likewise.
* gnu/packages/wordnet.scm (wordnet): Likewise.
* gnu/packages/xml.scm (libxml2):Likewise.