pgsql: Adjust string comparison so that only bitwise-equal strings are

Log Message:
-----------
Adjust string comparison so that only bitwise-equal strings are considered
equal: if strcoll claims two strings are equal, check it with strcmp, and
sort according to strcmp if not identical.  This fixes inconsistent
behavior under glibc's hu_HU locale, and probably under some other locales
as well.  Also, take advantage of the now-well-defined behavior to speed up
texteq, textne, bpchareq, bpcharne: they may as well just do a bitwise
comparison and not bother with strcoll at all.

NOTE: affected databases may need to REINDEX indexes on text columns to be
sure they are self-consistent.

Tags:
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REL8_0_STABLE

Modified Files:
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    pgsql/src/backend/utils/adt:
        varchar.c (r1.108 -> r1.108.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/varchar.c.diff?r1=1.108&r2=1.108.4.1)
        varlena.c (r1.118 -> r1.118.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/varlena.c.diff?r1=1.118&r2=1.118.4.1)