pgsql: Avoid direct cross-module links in hstore_plperl and ltree_plpyt

Avoid direct cross-module links in hstore_plperl and ltree_plpython, too.

Just turning the crank on the project started in commit d51924be8.
These cases turn out to be exact subsets of the boilerplate needed
for hstore_plpython.

Discussion: <2652(dot)1475512158(at)sss(dot)pgh(dot)pa(dot)us>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/eda04886c1e048d695728206504ab4198462168e

Modified Files
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contrib/hstore_plperl/Makefile | 16 +++----
contrib/hstore_plperl/hstore_plperl--1.0.sql | 5 ---
contrib/hstore_plperl/hstore_plperl.c | 54 ++++++++++++++++++++++++
contrib/hstore_plperl/hstore_plperlu--1.0.sql | 5 ---
contrib/ltree_plpython/Makefile | 19 ++++-----
contrib/ltree_plpython/ltree_plpython.c | 29 +++++++++++++
contrib/ltree_plpython/ltree_plpython2u--1.0.sql | 5 ---
contrib/ltree_plpython/ltree_plpython3u--1.0.sql | 5 ---
contrib/ltree_plpython/ltree_plpythonu--1.0.sql | 5 ---
src/tools/msvc/Mkvcbuild.pm | 3 +-
10 files changed, 102 insertions(+), 44 deletions(-)