pgsql: Include contrib modules in the temp installation even without RE

Include contrib modules in the temp installation even without REGRESS.

Now that we have TAP tests, a contrib module may have something useful
to do in "make check" even if it has no pg_regress-style regression
scripts, and hence no REGRESS setting. But the TAP tests will fail,
or else test the wrong installed files, unless we install the contrib
module into the temp installation. So move the bit about adding to
EXTRA_INSTALL so that it applies regardless.

We might want this in back branches in future, but for the moment
I only risked adding it to v11.

Discussion: https://postgr.es/m/12438.1535488750@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/42e61c7748eb36b75a05bd0a9a35c370c70a86c8

Modified Files
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src/makefiles/pgxs.mk | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)