pgsql: Backpatch "Use the preferred version of xsubpp."

Backpatch "Use the preferred version of xsubpp."

As requested this is backpatched all the way to release 8.2.

Branch
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REL8_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/322fc5cf569da335e46e9b8ff1b0f5c9e1847d94

Modified Files
--------------
src/pl/plperl/GNUmakefile | 5 ++++-
src/tools/msvc/Mkvcbuild.pm | 6 ++++--
2 files changed, 8 insertions(+), 3 deletions(-)