noweb (fix formula)

No files from the `icon` directory were not being installed. This
prevented correct functionality. Now they are installed.

Formula/noweb.rb

@@ -27,6 +27,11 @@ class Noweb < Formula
       man.mkpath
       (texmf/'tex/generic/noweb').mkpath
 
+      system "make", "install", "BIN=#{bin}",
+                                "LIB=#{lib}",
+                                "MAN=#{man}",
+                                "TEXINPUTS=#{texmf}/tex/generic/noweb"
+      cd "icon" do
         system "make", "install", "BIN=#{bin}",
                                   "LIB=#{lib}",
                                   "MAN=#{man}",
@@ -34,3 +39,4 @@ class Noweb < Formula
       end
     end
   end
+end