pgsql: meson: Set up absolute rpaths to libdir

meson: Set up absolute rpaths to libdir

While I (Andres) had planned to use relative rpaths, it looks like agreeing on
the precise path might take a bit. So set up absolute rpaths for now.

I'm pushing this fairly quickly after posting the patch as several hackers
fought with this issue.

Discussion: https://postgr.es/m/20220927011951.j3h4o7n6bhf7dwau@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a1860071b3fc6b9475a09f0c306e432249bb8314

Modified Files
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meson.build | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)