Fix couchdb by fixing icu4c install_names

Bad icu4c, but this presses the point that we should be in general fixing stuff when it is installed. This code can be generalised, but there are some caveats.

Formula/icu4c.rb

@@ -22,6 +22,26 @@ class Icu4c <Formula
       system "make"
       system "make install"
     end
+
+    # fix install_names
+    lib.children.reject{ |pn| pn.symlink? or pn.extname != '.dylib' }.each do |dylib|
+      bad_names(dylib) do |id, bad_names|
+        cd lib do
+          system "install_name_tool", "-id", (lib+id).realpath, dylib.basename
+          bad_names.each do |bad|
+            system "install_name_tool", "-change", bad, (lib+bad.basename).realpath, dylib.basename
+          end
+        end
+      end
+    end
+  end
+
+  def bad_names pn
+    ENV['HOMEBREW_PN'] = pn.to_s
+    rx = /\t(.*) \(compatibility version (\d+\.)*\d+, current version (\d+\.)*\d+\)/
+    dylibs = `otool -L "$HOMEBREW_PN"`.split "\n"
+    dylibs = dylibs.map{ |fn| rx =~ fn && $1 }.compact.reject{ |fn| fn[0].chr == '/' }.map{ |fn| p fn; Pathname.new fn }
+    yield dylibs.shift, dylibs
   end
 end