The last element of sw::Constants::maxPos was inadvertently 0x7F7FFFFE
instead of 0x7F7FFFFF. Replace it with a scalar which is broadcast to
all elements within Reactor code.

Bug: b/175073806
Change-Id: Ia82cfe199bb2ea85367c6ff4f59b31e2acf5c6f2
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/50988Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>