pgsql: Prevent locale-aware handling of upper, lower, and initcap when

Log Message:
-----------
Prevent locale-aware handling of upper, lower, and initcap when the
locale is C.

Backpatch to 8.0.X because some operating systems were throwing errors
for such operations, rather than ignoring the locale when it was C.

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        oracle_compat.c (r1.57 -> r1.58)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/oracle_compat.c.diff?r1=1.57&r2=1.58)
        pg_locale.c (r1.30 -> r1.31)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/pg_locale.c.diff?r1=1.30&r2=1.31)
    pgsql/src/include/utils:
        pg_locale.h (r1.19 -> r1.20)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/pg_locale.h.diff?r1=1.19&r2=1.20)