Add some tests for constants
Add some tests for constants

ssarangi/llvmlite,pitrou/llvmlite,ssarangi/llvmlite,ssarangi/llvmlite,sklam/llvmlite,pitrou/llvmlite,m-labs/llvmlite,sklam/llvmlite,m-labs/llvmlite,numba/llvmlite,markdewing/llvmlite,markdewing/llvmlite,numba/llvmlite,m-labs/llvmlite,sklam/llvmlite,m-labs/llvmlite,squisher/llvmlite,squisher/llvmlite,pitrou/llvmlite,numba/llvmlite,squisher/llvmlite,markdewing/llvmlite,sklam/llvmlite,numba/llvmlite,markdewing/llvmlite,squisher/llvmlite,ssarangi/llvmlite,pitrou/llvmlite