More improvements for Ruby support in 'etags'

More improvements for Ruby support in 'etags'

* lib-src/etags.c (Ruby_functions): Tag Ruby accessors and
alias_method.  Identify constants even if the assignment is not
followed by whitespace.  (Bug#22241)

* test/etags/ruby-src/test1.ruby: Add tests for constants,
accessors, and alias_method.
* test/etags/ETAGS.good_1:
* test/etags/ETAGS.good_2:
* test/etags/ETAGS.good_3:
* test/etags/ETAGS.good_4:
* test/etags/ETAGS.good_5:
* test/etags/ETAGS.good_6:
* test/etags/CTAGS.good: Adapt to changes in Ruby tests.