envutil.rb: skip if load failed

* test/lib/envutil.rb (assert_no_memory_leak): skip when failed to
  load fiddle.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48598 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_const.rb: use assert_warning

* test/ruby/test_const.rb (test_redefinition): should use
  assert_warning for warning message test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48599 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
generic_erb.rb: read in binary mode

* tool/generic_erb.rb: read existing file in binary mode to
  convert nothing.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48600 b2dd03c8-39d4-4d8f-98ff-823fe69b080e