opencv - --build32 option; needed for some cameras

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

Formula/opencv.rb

@@ -21,8 +21,14 @@ class Opencv <Formula
   # you don't need unless you're doing video analysis, and some of it isn't
   # in Homebrew anyway.
 
+  def options
+    [['--build32', 'Force a 32-bit build.']]
+  end
+
   def install
-    system "cmake -G 'Unix Makefiles' -DCMAKE_INSTALL_PREFIX:PATH=#{prefix} ."
+    makefiles = "cmake -G 'Unix Makefiles' -DCMAKE_INSTALL_PREFIX:PATH=#{prefix} ."
+    makefiles += " -DOPENCV_EXTRA_C_FLAGS='-arch i386 -m32'" if ARGV.include? '--build32'
+    system makefiles
     system "make"
     system "make install"
   end