Support '=' in Scheme and Lisp tags in 'etags'

Support '=' in Scheme and Lisp tags in 'etags'

* lib-src/etags.c (get_lispy_tag): New function.
(L_getit, Scheme_functions): Use get_lispy_tag (Bug#5624).
* test/manual/etags/CTAGS.good:
* test/manual/etags/ETAGS.good_1:
* test/manual/etags/ETAGS.good_2:
* test/manual/etags/ETAGS.good_3:
* test/manual/etags/ETAGS.good_4:
* test/manual/etags/ETAGS.good_5:
* test/manual/etags/ETAGS.good_6:
* test/manual/etags/Makefile:
* test/manual/etags/el-src/TAGTEST.EL: Update tests.
* test/manual/etags/scm-src/test.scm: New tests for Scheme.