Remove use of rand in peakflops

Add an assertion for correctness too.
Address #10349

base/linalg/generic.jl

@@ -336,10 +336,11 @@ scale!(b::AbstractVector, A::AbstractMatrix) = scale!(A,b,A)
 #findmin(a::AbstractArray)
 
 function peakflops(n::Integer=2000; parallel::Bool=false)
-    a = rand(100,100)
-    t = @elapsed a*a
-    a = rand(n,n)
-    t = @elapsed a*a
+    a = ones(Float64,100,100)
+    t = @elapsed a2 = a*a
+    a = ones(Float64,n,n)
+    t = @elapsed a2 = a*a
+    @assert a2[1,1] == n
     parallel ? sum(pmap(peakflops, [ n for i in 1:nworkers()])) : (2*Float64(n)^3/t)
 end