ruby: refactor package to use more macros

ruby: refactor package to use more macros

ruby subpackages now are generated by a macro. This reduces the
Makefile size by half and the chance of errors.

No change in packages contents, install-size or dependencies, except
for some removed doc files.

Improved ruby_missingfiles and ruby_find_pkgsdeps script

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>