Fix some issues at get_abi.pl script

This series replace this patch:

	https://lore.kernel.org/linux-doc/[email protected]/T/#t

It turns that there were multiple bugs at the get_abi.pl code that create cross-references.

Patches 1 to 6 fix those issues, and should apply cleanly on the top of the docs tree (although I tested against next-20210323).

Patch 7 is optional, and independent from the other patches. It is meant to be applied against akpm's tree. It makes the description (IMHO) clearer, while producing cross references for the two mentioned symbols.

The fix patches are:

patch 1: fix some regexes that match the symbols that need to be
escaped when parsing "What:". The same regex is also used when generating cross-references;

patch 2: makes the check for Documentation/ABI references more
robust, as right now, it stops at the first occurrence;

patch 3: fix the parser for /sys/foo -> xref conversion. Basically,
the logic that seeks for start and end boundaries were broken. The new logic is a way more robust.

patch 4: generate cross-references for /config/foo and other less
common ABI occurrences;

patch 5 and 6: don't generate cross-references inside literal blocks.
Right now, there are a couple of places that would otherwise generate references, producing a bad output.

Mauro Carvalho Chehab (7):
scripts: get_abi.pl: better handle escape chars on what:
get_abi.pl: seek for all occurrences for Documentation/ABI get_abi.pl: fix xref boundaries
scripts: get_abi.pl: extend xref match to other types
scripts: get_abi.pl: parse description line per line
scripts: get_abi: ignore code blocks for cross-references
ABI: sysfs-kernel-mm-cma: fix two cross-references

 Documentation/ABI/testing/sysfs-kernel-mm-cma |  8 +-
 scripts/get_abi.pl                            | 76 +++++++++++++------
 2 files changed, 57 insertions(+), 27 deletions(-)

2.30.2