pgsql: Remove duplicate variable initializations identified by clang

Log Message:
-----------
Remove duplicate variable initializations identified by clang static checker.
One of these represents a nontrivial bug (a promptly-leaked palloc), so
backpatch.

Greg Stark

Tags:
----
REL8_4_STABLE

Modified Files:
--------------
    pgsql/src/backend/tsearch:
        regis.c (r1.7 -> r1.7.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/regis.c?r1=1.7&r2=1.7.2.1)
        ts_parse.c (r1.12 -> r1.12.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/ts_parse.c?r1=1.12&r2=1.12.2.1)
    pgsql/src/backend/utils/adt:
        encode.c (r1.23 -> r1.23.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/encode.c?r1=1.23&r2=1.23.2.1)