fix updatex_eachindex.

Author: alsam

benchmark/benchmarks.jl

@@ -10,7 +10,7 @@ fillx() = for i = 1:2*dim x[i] = i end
 filly() = for i = -dim+1:dim y[i] = i end
 updatex() = for i = 1:2*dim x[i] = x[i] + i end
 updatey() = for i = -dim+1:dim y[i] = y[i] + i end
-updatex_eachindex() = for i in eachindex(x) x[i] + i end
+updatex_eachindex() = for i in eachindex(x) x[i] = x[i] + i end
 updatey_eachindex() = for i in eachindex(y) y[i] = y[i] + i end
 
 @benchmark fillx()