main: rename goroutine tests

While LLVM coroutines are one implementation of goroutines, it is not
the only one. Therefore, rename the tests to 'goroutines' to better
describe what they're for.

main_test.go

@@ -35,9 +35,9 @@ func TestCompiler(t *testing.T) {
 		"calls.go",
 		"cgo/",
 		"channel.go",
-		"coroutines.go",
 		"float.go",
 		"gc.go",
+		"goroutines.go",
 		"init.go",
 		"init_multi.go",
 		"interface.go",