pgsql: When using GCC on AMD64 and PPC, ECPGget_variable() takes a

Log Message:
-----------
When using GCC on AMD64 and PPC, ECPGget_variable() takes a va_list *, not
a va_list. Christof Petig's previous patch made this change, but neglected
to update ecpglib/descriptor.c, resulting in a compiler warning (and a
likely runtime crash) on AMD64 and PPC.

Tags:
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REL8_1_STABLE

Modified Files:
--------------
    pgsql/src/interfaces/ecpg/ecpglib:
        descriptor.c (r1.12.6.1 -> r1.12.6.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ecpglib/descriptor.c.diff?r1=1.12.6.1&r2=1.12.6.2)