wasi: try to make Test_Nonblock less flaky (#1506)

Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>

imports/wasi_snapshot_preview1/testdata/zig-cc/wasi.c

@@ -165,7 +165,7 @@ void main_sock() {
 void main_nonblock(char* fpath) {
   struct timespec tim, tim2;
   tim.tv_sec = 0;
-  tim.tv_nsec = 200 * 1000000;
+  tim.tv_nsec = 100 * 1000000; // 100 msec
   int fd = open(fpath, O_RDONLY | O_NONBLOCK);
   char buf[32];
   ssize_t newLen = 0;

imports/wasi_snapshot_preview1/wasi_stdlib_unix_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/api"
 	"github.com/tetratelabs/wazero/internal/testing/require"
 )
 
@@ -26,8 +27,16 @@ func Test_Nonblock(t *testing.T) {
 	err := syscall.Mkfifo(fifoAbsPath, 0o666)
 	require.NoError(t, err)
 
-	ch := make(chan string, 1)
-	go func() { ch <- compileAndRun(t, testCtx, moduleConfig, wasmZigCc) }()
+	ch := make(chan string, 2)
+	go func() {
+		ch <- compileAndRunWithPreStart(t, testCtx, moduleConfig, wasmZigCc, func(t *testing.T, mod api.Module) {
+			// Send a dummy string to signal that initialization has completed.
+			ch <- "ready"
+		})
+	}()
+
+	// Wait for the dummy value, then start the sleep.
+	require.Equal(t, "ready", <-ch)
 
 	// The test writes a few dots on the console until the pipe has data ready for reading,
 	// so we wait for a little to ensure those dots are printed.