avr: get go test -target=simavr to work

This patch changes two things:

 1. It changes the default stack size. Without this change, the
    goroutine.go test doesn't pass (apparently there's some memory
    corruption).
 2. It moves the excluded tests so that they are skipped with a regular
    `-target=simavr`, not just when running all tests (without
    `-target`).

main_test.go

@@ -146,46 +146,7 @@ func TestBuild(t *testing.T) {
 		// LIBCLANG FATAL ERROR: Cannot select: t3: i16 = JumpTable<0>
 		// This bug is non-deterministic.
 		t.Skip("skipped due to non-deterministic backend bugs")
-
-		var avrTests []string
-		for _, t := range tests {
-			switch t {
-			case "atomic.go":
-				// Requires GCC 11.2.0 or above for interface comparison.
-				// https://github.com/gcc-mirror/gcc/commit/f30dd607669212de135dec1f1d8a93b8954c327c
-
-			case "reflect.go":
-				// Reflect tests do not work due to type code issues.
-
-			case "gc.go":
-				// Does not pass due to high mark false positive rate.
-
-			case "json.go", "stdlib.go", "testing.go":
-				// Breaks interp.
-
-			case "map.go":
-				// Reflect size calculation crashes.
-
-			case "binop.go":
-				// Interface comparison results are inverted.
-
-			case "channel.go":
-				// Freezes after recv from closed channel.
-
-			case "float.go", "math.go", "print.go":
-				// Stuck in runtime.printfloat64.
-
-			case "interface.go":
-				// Several comparison tests fail.
-
-			case "cgo/":
-				// CGo does not work on AVR.
-
-			default:
-				avrTests = append(avrTests, t)
-			}
-		}
-		runPlatTests(optionsFromTarget("simavr", sema), avrTests, t)
+		runPlatTests(optionsFromTarget("simavr", sema), tests, t)
 	})
 
 	if runtime.GOOS == "linux" {
@@ -217,6 +178,54 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 	}
 
 	for _, name := range tests {
+		if options.Target == "simavr" {
+			// Not all tests are currently supported on AVR.
+			// Skip the ones that aren't.
+			switch name {
+			case "atomic.go":
+				// Requires GCC 11.2.0 or above for interface comparison.
+				// https://github.com/gcc-mirror/gcc/commit/f30dd607669212de135dec1f1d8a93b8954c327c
+				continue
+
+			case "reflect.go":
+				// Reflect tests do not work due to type code issues.
+				continue
+
+			case "gc.go":
+				// Does not pass due to high mark false positive rate.
+				continue
+
+			case "json.go", "stdlib.go", "testing.go", "testing_go118.go":
+				// Breaks interp.
+				continue
+
+			case "map.go":
+				// Reflect size calculation crashes.
+				continue
+
+			case "binop.go":
+				// Interface comparison results are inverted.
+				continue
+
+			case "channel.go":
+				// Freezes after recv from closed channel.
+				continue
+
+			case "float.go", "math.go", "print.go":
+				// Stuck in runtime.printfloat64.
+				continue
+
+			case "interface.go":
+				// Several comparison tests fail.
+				continue
+
+			case "cgo/":
+				// CGo does not work on AVR.
+				continue
+
+			default:
+			}
+		}
 		name := name // redefine to avoid race condition
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()

targets/simavr.json

@@ -1,5 +1,5 @@
 {
     "inherits": ["atmega1284p"],
     "scheduler": "tasks",
-    "default-stack-size": 512
+    "default-stack-size": 384
 }