pgsql: Add new make targets world-bin and install-world-bin

Add new make targets world-bin and install-world-bin

These are the same as world and install-world respectively, but without
building or installing the documentation. There are many reasons for
wanting to be able to do this, including speed, lack of documentation
building tools, and wanting to build other formats of the documentation.
Plans for simplifying the buildfarm client code include using these
targets.

Backpatch to all live branches.

Discussion: https://postgr.es/m/6a421136-d462-b043-a8eb-e75b2861f3df@dunslane.net

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/c71471c96f1682d133dd718ed5129f0be7ebb295

Modified Files
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GNUmakefile.in                 | 10 ++++++++++
doc/src/sgml/installation.sgml | 15 +++++++++++++++
2 files changed, 25 insertions(+)