fix ccall test for not-found library output

test/ccall.jl

@@ -1554,15 +1554,15 @@ let
 end
 
 # issue #34061
-o_file = tempname()
-output = read(Cmd(`$(Base.julia_cmd()) --output-o=$o_file -e 'Base.reinit_stdio();
- f() = ccall((:dne, :does_not_exist), Cvoid, ());
- f()'`; ignorestatus=true), String)
-@test occursin(output, """
-ERROR: could not load library "does_not_exist"
-does_not_exist.so: cannot open shared object file: No such file or directory
-""")
-@test !isfile(o_file)
+let o_file = tempname(), err = Base.PipeEndpoint()
+ run(pipeline(Cmd(`$(Base.julia_cmd()) --output-o=$o_file -e 'Base.reinit_stdio();
+  f() = ccall((:dne, :does_not_exist), Cvoid, ());
+  f()'`; ignorestatus=true), stderr=err), wait=false)
+ output = read(err, String)
+ @test occursin("""ERROR: could not load library "does_not_exist"
+ """, output)
+ @test !isfile(o_file)
+end
 
 # pass NTuple{N,T} as Ptr{T}/Ref{T}
 let