Merge branch 'mauro' into docs-mw

Mauro says:

This patch series change how kdoc parser handles macro replacements.

Instead of heavily relying on regular expressions that can sometimes
be very complex, it uses a C lexical tokenizer. This ensures that
BEGIN/END blocks on functions and structs are properly handled,
even when nested.

Checking before/after the patch series, for both man pages and
rst only had:
    - whitespace differences;
    - struct_group macros now are shown as inner anonimous structs
      as it should be.

Also, I didn't notice any relevant change on the documentation build
time. With that regards, right now, every time a CMatch replacement
rule takes in place, it does:

    for each transform:
    - tokenizes the source code;
    - handle CMatch;
    - convert tokens back to a string.

A possible optimization would be to do, instead:

    - tokenizes source code;
    - for each transform handle CMatch;
    - convert tokens back to a string.

For now, I opted not do do it, because:

    - too much changes on a single row;
    - docs build time is taking ~3:30 minutes, which is
      about the same time it ws taken before the changes;
    - there is a very dirty hack inside function_xforms:
	 (KernRe(r"_noprof"), ""). This is meant to change
      function prototypes instead of function arguments.

So, if ok for you, I would prefer to merge this one first. We can later
optimize kdoc_parser to avoid multiple token <-> string conversions.

-

One important aspect of this series is that it introduces unittests
for kernel-doc. I used it a lot during the development of this series,
to ensure that the changes I was doing were producing the expected
results. Tests are on two separate files that can be executed directly.

Alternatively, there is a run.py script that runs all of them (and
any other python script named  tools/unittests/test_*.py"):

  $ tools/unittests/run.py
  test_cmatch:
      TestSearch:
	  test_search_acquires_multiple:                               OK
	  test_search_acquires_nested_paren:                           OK
	  test_search_acquires_simple:                                 OK
	  test_search_must_hold:                                       OK
	  test_search_must_hold_shared:                                OK
	  test_search_no_false_positive:                               OK
	  test_search_no_function:                                     OK
	  test_search_no_macro_remains:                                OK
      TestSubMultipleMacros:
	  test_acquires_multiple:                                      OK
	  test_acquires_nested_paren:                                  OK
	  test_acquires_simple:                                        OK
	  test_mixed_macros:                                           OK
	  test_must_hold:                                              OK
	  test_must_hold_shared:                                       OK
	  test_no_false_positive:                                      OK
	  test_no_function:                                            OK
	  test_no_macro_remains:                                       OK
      TestSubSimple:
	  test_rise_early_greedy:                                      OK
	  test_rise_multiple_greedy:                                   OK
	  test_strip_multiple_acquires:                                OK
	  test_sub_count_parameter:                                    OK
	  test_sub_mixed_placeholders:                                 OK
	  test_sub_multiple_placeholders:                              OK
	  test_sub_no_placeholder:                                     OK
	  test_sub_single_placeholder:                                 OK
	  test_sub_with_capture:                                       OK
	  test_sub_zero_placeholder:                                   OK
      TestSubWithLocalXforms:
	  test_functions_with_acquires_and_releases:                   OK
	  test_raw_struct_group:                                       OK
	  test_raw_struct_group_tagged:                                OK
	  test_struct_group:                                           OK
	  test_struct_group_attr:                                      OK
	  test_struct_group_tagged_with_private:                       OK
	  test_struct_kcov:                                            OK
	  test_vars_stackdepot:                                        OK

  test_tokenizer:
      TestPublicPrivate:
	  test_balanced_inner_private:                                 OK
	  test_balanced_non_greddy_private:                            OK
	  test_balanced_private:                                       OK
	  test_no private:                                             OK
	  test_unbalanced_inner_private:                               OK
	  test_unbalanced_private:                                     OK
	  test_unbalanced_struct_group_tagged_with_private:            OK
	  test_unbalanced_two_struct_group_tagged_first_with_private:  OK
	  test_unbalanced_without_end_of_line:                         OK
      TestTokenizer:
	  test_basic_tokens:                                           OK
	  test_depth_counters:                                         OK
	  test_mismatch_error:                                         OK

  Ran 47 tests