pgsql: Allow underscores in tsearch email addressses, per RFC 5322 and

Log Message:
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Allow underscores in tsearch email addressses, per RFC 5322 and report
by Dan O'Hara.

Patch by Teodor Sigaev

Modified Files:
--------------
pgsql/src/backend/tsearch:
wparser_def.c (r1.27 -> r1.28)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/tsearch/wparser_def.c?r1=1.27&r2=1.28)