[gdb/testsuite, tclint] Further tclint fixing

[gdb/testsuite, tclint] Further tclint fixing

Currently stable tclint (v6.0.1) as used in pre-commit doesn't check code that
is passed as arguments to commands specific to the gdb testsuite [1], like
with_test_prefix:
...
with_test_prefix foo {
  ...
}
...

I wrote a rudimentary tclint patch handling this, skipping the dwarf assembler
procs.

Fix the additional issues found.

[1] https://github.com/nmoroze/tclint/issues/121