Assert if timezone name is truncated

See emscripten-core#21582

Author: sbc100

src/library.js

@@ -651,6 +651,10 @@ addToLibrary({
     };
     var winterName = extractZone(winter);
     var summerName = extractZone(summer);
+#if ASSERTIONS
+    assert(lengthBytesUTF8(winterName) <= {{{ cDefs.TZNAME_MAX }}}, `timezone name truncated to fix in TZNAME_MAX (${winterName})`);
+    assert(lengthBytesUTF8(summerName) <= {{{ cDefs.TZNAME_MAX }}}, `timezone name truncated to fix in TZNAME_MAX (${summerName})`);
+#endif
     if (summerOffset < winterOffset) {
       // Northern hemisphere
       stringToUTF8(winterName, std_name, {{{ cDefs.TZNAME_MAX + 1 }}});

test/test_core.py

@@ -2656,6 +2656,7 @@ def test_strptime_reentrant(self):
     self.set_setting('EXIT_RUNTIME')
     self.do_core_test('test_strptime_reentrant.c')
 
+  @crossplatform
   def test_strftime(self):
     self.do_core_test('test_strftime.c')