When constructing the virtual MATCH term of the WHERE clause for a virtual

When constructing the virtual MATCH term of the WHERE clause for a virtual
table that is in a LEFT JOIN, be sure to set the correct Expr.iRightJoinTable
value.  This value does not appear to ever be used, except inside of a single
assert().  But it is good to set it correctly, nevertheless.  This fixes
ticket [7929c1efb2d67e98], which as far as I can tell is completely harmless.

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