PRINCE: Fix potential out-of-bounds write (CID 1248504)

There are kMaxTexts text slots, so kMaxTexts itself is not valid.
PRINCE: Fix potential out-of-bounds reads (CID 1248500, 1248503)

Since heroSetTable[] is an array of int, use >= ARRAYSIZE() instead
of > sizeof().
PRINCE: Fix potential out-of-bounds read (CID 1248502)

Since _opcodes[] has kNumOpcodes elements, kNumOpcodes itself is
not a valid index.