It loads `ext/fiddle/lib/fiddle/version.rb`, which causes constant
redefinition warning:
http://rubyci.s3.amazonaws.com/ubuntu2004/ruby-master/log/20200523T153003Z.log.html.gz
```
[ 6317/20193] TestDefaultGems#test_validate_gemspec/home/chkbuild/chkbuild/tmp/build/20200523T153003Z/ruby/ext/fiddle/lib/fiddle/version.rb:2: warning: already initialized constant Fiddle::VERSION
/home/chkbuild/chkbuild/tmp/build/20200523T153003Z/ruby/.ext/common/fiddle/version.rb:2: warning: previous definition of VERSION was here
= 0.16 s
```
This changeset read the version by manual parsing hack which is also
used in stringio and zlib.
Added following gemspecs.
* extensions: date, dbm, etc, fiddle, gdbm, sdbm, stringio, strscan, zlib
* pure ruby libraries: cmath, csv, fileutils, scanf, webrick
psych and rdoc is out of scope of this commit. I will merge after
upstream was change to `frozen_string_literal: true`.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59115 b2dd03c8-39d4-4d8f-98ff-823fe69b080e