ruby: Add back needed patch

packages/ruby/tool-rbinstall.rb.patch

@@ -0,0 +1,21 @@
+diff -u -r ../ruby-2.3.0/tool/rbinstall.rb ./tool/rbinstall.rb
+--- ../ruby-2.3.0/tool/rbinstall.rb    2015-11-16 01:33:17.000000000 -0500
++++ ./tool/rbinstall.rb        2015-12-25 15:43:04.756646343 -0500
+@@ -696,7 +696,7 @@
+ # :startdoc:
+
+ install?(:ext, :comm, :gem) do
+-  gem_dir = Gem.default_dir
++  gem_dir = "@TERMUX_PREFIX@/lib/ruby/gems/2.4.0"
+   directories = Gem.ensure_gem_subdirectories(gem_dir, :mode => $dir_mode)
+   prepare "default gems", gem_dir, directories
+
+@@ -732,7 +732,7 @@
+ end
+
+ install?(:ext, :comm, :gem) do
+-  gem_dir = Gem.default_dir
++  gem_dir = "@TERMUX_PREFIX@/lib/ruby/gems/2.4.0"
+   directories = Gem.ensure_gem_subdirectories(gem_dir, :mode => $dir_mode)
+   prepare "bundle gems", gem_dir, directories
+   install_dir = with_destdir(gem_dir)