pgsql: meson: portname was set too early

meson: portname was set too early

portname is set to host_system, but host_system might still be changed
later in the file.  As a consequence, platforms where host_system is
changed later wouldn't find some of their platform-specific files
(driven by portname), and the build would fail.  Move the assignment
of portname further down after the last change of host_system (but
before further overriding assignments to portname).

Discussion:
https://www.postgresql.org/message-id/flat/CAC7zN94TdsHhY88XkroJzSMx7E%3DBQpV9LKKjNSEnTM04ihoWCA%40mail.gmail.com

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/8b31b689f4db9fca726a8d1bab20b89ebb3fa0b1

Modified Files
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meson.build | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)