docs: Better handle kernel-doc class

Currently, there is an issue with kernel-doc KernelFiles class:
if one tries to add a kernel-doc tag to a non-existing file, it will produce a KeyError, as KernelFiles.msg() will try to pick a key from a non-existing file. Add a check to prevent such error.

With that, building docs with broken files will work as before(*):

	$ make htmldocs
	...
	Cannot find file ./drivers/gpio/gpiolib-acpi.c
	Cannot find file ./drivers/gpio/gpiolib-acpi.c
	No kernel-doc for file ./drivers/gpio/gpiolib-acpi.c
	...
	Documentation/arch/powerpc/htm.rst: WARNING: document isn't included in any toctree

While here, also better handle errors at the kernel-doc classes.

(*) IMO, this is the wrong behavior, but let's discuss it in separate.

Mauro Carvalho Chehab (2):
scripts: kernel-doc: prevent a KeyError when checking output
docs: kerneldoc.py: add try/except blocks for kernel-doc class errors

 Documentation/sphinx/kerneldoc.py | 21 +++++++++++++++++----
 scripts/lib/kdoc/kdoc_files.py    |  4 ++++
 2 files changed, 21 insertions(+), 4 deletions(-)

2.49.0