pgsql: Fix parse tree of DROP TRANSFORM and COMMENT ON TRANSFORM

Fix parse tree of DROP TRANSFORM and COMMENT ON TRANSFORM

The plain C string language name needs to be wrapped in makeString() so
that the parse tree is copyable.  This is detectable by
-DCOPY_PARSE_PLAN_TREES.  Add a test case for the COMMENT case.

Also make the quoting in the error messages more consistent.

discovered by Tom Lane

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0779f2ba2db6787259f3ea82f999e08552724218

Modified Files
--------------
contrib/hstore_plperl/expected/create_transform.out |    7 ++++---
contrib/hstore_plperl/sql/create_transform.sql      |    2 ++
src/backend/catalog/objectaddress.c                 |    2 +-
src/backend/commands/dropcmds.c                     |    4 ++--
src/backend/commands/functioncmds.c                 |    2 +-
src/backend/parser/gram.y                           |    6 +++---
6 files changed, 13 insertions(+), 10 deletions(-)