Fix overflowing cell in HTML table

sphinx-build defaults to the 'tabulary' environment for tables,
but uses regular 'tabular' for those involving literal blocks,
since tabulary does not handle them properly.  It seems that this
deficiency of tabulary also applies to inline literals, which
are rendered as \code{} sections by the latex builder.
Fortunately, sphinx provides a workaround to force a particular
column specification for the table.

The requirement for a table:: statement after the tabularcolumns::
statement is very poorly documented.

(cherry picked from commit da396d7603e949faec594036dee6de0e8f44bddb)

https://github.com/krb5/krb5/commit/993204158b81a6dd3798c308fe3cfa633346a4e1
Author: Ben Kaduk <kaduk@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 993204158b81a6dd3798c308fe3cfa633346a4e1
Branch: krb5-1.11
 doc/appdev/h5l_mit_apidiff.rst |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)