IntArray in c.h

I found the struct IntArray defined in c.h is actually used only in
execQual.c. ISTM the definition should be at least moved to the right
place.

Attached is a trivial fix. Addition to the explanation above,  I
replaced IntArray by simple int array bounded with MAXDIM and remove
local variable lIndex in ExecEvalArrayRef  because the usage of the
variable doesn't seem good to me.

Regression passed and various manual tests like "UPDATE t SET
a[1:2][1] = 1" didn't fail.


Regards,

-- 
Hitoshi Harada