Don't use bitcast+float path for integer constant values
Don't use bitcast+float path for integer constant values

LLVM takes liberties with NaN float constants, which can arise in integer
constant values.

Bug b/140294254

Test: dEQP-VK.spirv_assembly.type.vec3.u32.constant_composite_frag
Change-Id: Ibfff77b9e0bacf81756bb50801615369dfc51ab6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35728
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Tested-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>
Reviewed-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader