REGTESTS: stick-table: cover the remaining gpc and gpt spellings

REGTESTS: stick-table: cover the remaining gpc and gpt spellings

Thirteen spellings of the general purpose counters were still left out
of this test: the legacy sc1_ and sc2_ increments and clears, the sc1_
readers, sc0_inc_gpc0, sc0_clr_gpc0, sc_inc_gpc1(), sc_clr_gpc1() and
the generic sc_clr_gpc() of the array form, plus the whole src_inc_gpc*
and src_clr_gpc* family which the notes listed as a follow-up.

The first frontend cannot host them: its sc1 tracks the array table,
which the legacy fetches do not accept, and its counters already carry
the values the existing clients assert. A second frontend therefore
tracks one legacy table through its three counters, which makes the
aliasing visible since an increment through one of them is read back
through the other two, and a third frontend, whose counter tracks an
array table, is only there for the generic clear of the array form.