Add test for function arguments

Don't report captured function values:

    $ go test
    --- FAIL: Test (1.26s)
        analysistest.go:459: ./testdata/function_argument.go:5:3:
        unexpected diagnostic: captured reference callback in goroutine
        closure

1 files changed, 7 insertions, 0 deletions

diff --git a/testdata/function_argument.go b/testdata/function_argument.go
new file mode 100644
index 0000000..5a38ae2
--- /dev/null
+++ b/testdata/function_argument.go
@@ -0,0 +1,7 @@
+package main
+
+func functionArgument(callback func()) {
+	go func() {
+		callback()
+	}()
+}