pgsql: doc: Make libpq documentation navigable between functions

doc: Make libpq documentation navigable between functions

Turn most mentions of libpq functions into links.  At id attributes to
most libpq functions, where not existing yet, so that they can be
linked to.  (In a handful of cases there were problems with the PDF
processing toolchain, so those instances were not changed.)

Author: Fabien COELHO <coelho@cri.ensmp.fr>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/alpine.DEB.2.21.1905121032330.27203@lancre

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e829337d42d0e3c73ba9f380e81e51aab4865f8f

Modified Files
--------------
doc/src/sgml/ecpg.sgml  |   6 +-
doc/src/sgml/libpq.sgml | 796 ++++++++++++++++++++++++------------------------
doc/src/sgml/lobj.sgml  |   2 +-
3 files changed, 402 insertions(+), 402 deletions(-)