By default, etags produces unqualified Perl tag names

By default, etags produces unqualified Perl tag names

* lib-src/etags.c (Perl_functions): Produce unqualified names,
unless -Q was specified.
(print_help): Update the description of -Q.

* doc/man/etags.1: Update the documentation of -Q.

* 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/CTAGS.good: Adapt the expected test results to the
changed Perl functionality.