Fix interrupts during Ractor.select

Fixes [Bug #20168]

bootstraptest/test_ractor.rb

@@ -1466,6 +1466,25 @@ assert_equal '[:ok, :ok]', %q{
   end
 }
 
+# Ractor.select is interruptible
+assert_normal_exit %q{
+  trap(:INT) do
+    exit
+  end
+
+  r = Ractor.new do
+    loop do
+      sleep 1
+    end
+  end
+
+  Thread.new do
+    sleep 0.5
+    Process.kill(:INT, Process.pid)
+  end
+  Ractor.select(r)
+}
+
 # Ractor-local storage
 assert_equal '[nil, "b", "a"]', %q{
   ans = []

ractor.c

@@ -1804,17 +1804,17 @@ ractor_select_internal(rb_execution_context_t *ec, VALUE self, VALUE ractors, VA
     int state;
 
     EC_PUSH_TAG(ec);
-    if ((state = EC_EXEC_TAG() == TAG_NONE)) {
+    if ((state = EC_EXEC_TAG()) == TAG_NONE) {
         result = ractor_selector__wait(selector, do_receive, do_yield, yield_value, move);
     }
-    else {
+    EC_POP_TAG();
+    if (state != TAG_NONE) {
         // ensure
         ractor_selector_clear(selector);
 
         // jump
         EC_JUMP_TAG(ec, state);
     }
-    EC_POP_TAG();
 
     RB_GC_GUARD(ractors);
     return result;