[Note: Patch provided as an attachment to protect encoding/formatting.]

The current official docs mistakenly pick up the override macros
in libavcodec/tableprint_vlc.h as the canonical definitions of
functions like av_free() and av_freep(), causing the docs to
link to those #defines instead of the actual definitions of
the functions (in libavutil/mem.c, for the examples given).

Wrapping the rogue macros in a conditional documentation section
(arbitrarily named DOXYGEN_IGNORE), which is then NOT added to
the ENABLED_SECTIONS config in the Doxyfile, is the recommended
method of telling Doxygen to ignore some piece of code.

Ref: https://www.doxygen.nl/manual/faq.html#faq_code
Ref: https://www.doxygen.nl/manual/commands.html#cmdcond

Signed-off-by: FeRD (Frank Dana) <ferdnyc@gmail.com>