pgsql: meson: docs: Add xml{lint,proc} wrapper to collect dependencies

meson: docs: Add xml{lint,proc} wrapper to collect dependencies

meson/ninja do not support specifying dependencies via globs (as those make it
significantly more expensive to check the current build state). Instead
targets should emit dependency information when running that then can be
cheaply re-checked during future builds.

To handle xmllint and xsltproc invocations in the docs, add and use a wrapper
that uses --load-trace to collect dependency information.

Reviewed-by: Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>
Author: Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
Author: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://postgr.es/m/c5736f70-bb6d-8d25-e35c-e3d886e4e905@enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/29668e31865aa0442cd181ec7ee514295ef3578b

Modified Files
--------------
doc/src/sgml/meson.build | 41 +++++++++++++++++++++--------
doc/src/sgml/xmltools_dep_wrapper | 54 +++++++++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 11 deletions(-)