make success not error when nvcc isn't available

Author: SimonDanisch

src/backends/cudanative/cudanative.jl

@@ -146,7 +146,7 @@ immutable CUFunction{T}
     kernel::T
 end
 
-if success(`nvcc --version`)
+if try success(`nvcc --version`); catch false; end
     include("compilation.jl")
     hasnvcc() = true
 else

test/cudanative.jl

@@ -102,7 +102,7 @@ end
     jy = Array(y)
     @test map!(sin, jy, jy) ≈ Array(x)
 end
-
+#
 # if CUBackend.hasnvcc()
 #     @testset "Custom kernel from string function" begin
 #         x = GPUArray(rand(Float32, 100))