[PATCH] Pass COPT and PROFILE to CXXFLAGS as well

While working on making extension modules built reproducibly, I
noticed that extra flags passed via COPT (notably -ffile-prefix-map)
do not get added to CXXFLAGS.

This causes postgresql-hll to still store the full build path in the
.so file built:
https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/diffoscope-results/postgresql-hll.html

Christoph
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