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

Modified Files:
--------------
    pgsql/src/backend/tsearch:
        regis.c (r1.7 -> r1.8)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/regis.c?r1=1.7&r2=1.8)
        ts_parse.c (r1.14 -> r1.15)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/ts_parse.c?r1=1.14&r2=1.15)
    pgsql/src/backend/utils/adt:
        encode.c (r1.24 -> r1.25)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/encode.c?r1=1.24&r2=1.25)