We can call getVarFlags() instead of the multiple getVarFlag calls
which is a little more efficient. This reduces the number of overall
function calls so is good but probably isn't much faster (or slower).
(Bitbake rev: 505a4dd34e822bdf902d9b348dbcdf5b2c94e784)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>