renames fixtures as testdata to avoid spurious dependencies (#359)

testdata/argument-limit.go

@@ -0,0 +1,17 @@
+package fixtures
+
+func foo(a, b, c, d int) { // MATCH /maximum number of arguments per function exceeded; max 3 but got 4/
+
+}
+
+func bar(a, b int) {
+
+}
+
+func baz(a string, b int) {
+
+}
+
+func qux(a string, b int, c int, d string, e int64) { // MATCH /maximum number of arguments per function exceeded; max 3 but got 5/
+
+}