Add bunded gems on $LOAD_PATH.

Some test expects some gems to be available on $LOAD_PATH. For example,
RubyGem's test suite requires Rake.

This is currently rather naive implementation, since we don't have
RubyGems at hand to use something like
Gem::Specification#add_self_to_load_path.

test/runner.rb

@@ -4,6 +4,11 @@
 $LOAD_PATH << src_testdir
 $LOAD_PATH.unshift "#{src_testdir}/lib"
 
+# Get bundled gems on load path
+Dir.glob("#{src_testdir}/../gems/*/*.gemspec")
+  .reject {|f| f =~ /minitest|test-unit|power_assert/ }
+  .map {|f| $LOAD_PATH.unshift File.join(File.dirname(f), "lib") }
+
 require 'test/unit'
 
 module Gem