Give this condition a more revealing name
Move options to SoftwareSpec
Move dependencies to SoftwareSpec
Allow explicitly requiring universal deps

Previously, instructing Homebrew that all dependencies should be built
universal could be accomplished by redefining BuildOptions#universal? in
the class body:

  def build.universal?
    true
  end

However, the build object is no longer shared by all specs, so this is
insufficient. Instead, a new DSL method, "require_universal_deps", can
be used.

This feature is almost exclusively for wine, which requires universal
deps but does not itself have a universal option, since it is always
built 32-bit.
guile: use spec deps
asciidoc: use spec deps
mobile-shell: use spec deps
xmp: use spec deps
csync: use spec deps
libxml2: use spec deps
auctex: use spec deps
avrdude: use spec deps
blitz: use spec deps
ccache: use spec deps
cherokee: use spec deps
clucene: use spec deps
couchdb: use spec deps
ctags: use spec deps
czmq: use spec deps
dash: use spec deps