Add unsigned kext requirement.

Creates a new requirement that dictates packages are unable to install due to requiring a signed kext to function.

Closes Homebrew/homebrew#33404.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/requirements.rb

@@ -2,11 +2,12 @@ require 'requirement'
 require 'requirements/fortran_dependency'
 require 'requirements/language_module_dependency'
 require 'requirements/minimum_macos_requirement'
+require 'requirements/maximum_macos_requirement'
 require 'requirements/mpi_dependency'
 require 'requirements/osxfuse_dependency'
 require 'requirements/python_dependency'
+require 'requirements/unsigned_kext_requirement'
 require 'requirements/x11_dependency'
-require 'requirements/maximum_macos_requirement'
 
 class XcodeDependency < Requirement
   fatal true

Library/Homebrew/requirements/unsigned_kext_requirement.rb

+require 'requirement'
+
+class UnsignedKextRequirement < Requirement
+  fatal true
+
+  satisfy { MacOS.version < :yosemite }
+
+  def message
+    <<-EOS.undent
+      OS X Mavericks or older is required for this package.
+      OS X Yosemite introduced a strict unsigned kext ban which breaks this package.
+      You should remove this package from your system and attempt to find upstream
+      binaries to use instead.
+    EOS
+  end
+end