Fix harfbuzz build after new clang warning was added. NFC

Followup to emscripten-core#22798

Author: sbc100

src/library_stack_trace.js

@@ -5,13 +5,11 @@
  */
 
 var LibraryStackTrace = {
-  $jsStackTrace: function() {
-    return new Error().stack.toString();
-  },
+  $jsStackTrace: () => new Error().stack.toString(),
 
   $getCallstack__deps: ['$jsStackTrace', '$warnOnce'],
   $getCallstack__docs: '/** @param {number=} flags */',
-  $getCallstack: function(flags) {
+  $getCallstack: (flags) => {
     var callstack = jsStackTrace();
 
     // Find the symbols in the callstack that corresponds to the functions that
@@ -99,7 +97,7 @@ var LibraryStackTrace = {
   },
 
   emscripten_get_callstack__deps: ['$getCallstack', '$lengthBytesUTF8', '$stringToUTF8'],
-  emscripten_get_callstack: function(flags, str, maxbytes) {
+  emscripten_get_callstack: (flags, str, maxbytes) => {
     var callstack = getCallstack(flags);
     // User can query the required amount of bytes to hold the callstack.
     if (!str || maxbytes <= 0) {
@@ -205,7 +203,7 @@ var LibraryStackTrace = {
   // must be able to unwind from a PC value that may no longer be on the
   // execution stack, and so we are forced to cache the entire call stack.
   emscripten_stack_snapshot__deps: ['$convertFrameToPC', '$UNWIND_CACHE', '$saveInUnwindCache', '$jsStackTrace'],
-  emscripten_stack_snapshot: function() {
+  emscripten_stack_snapshot: () => {
     var callstack = jsStackTrace().split('\n');
     if (callstack[0] == 'Error') {
       callstack.shift();

tools/ports/harfbuzz.py

@@ -111,6 +111,7 @@ def create(final):
     -fno-exceptions
     -O3
     -DNDEBUG
+    -Wno-nontrivial-memaccess
     '''.split()
 
     cflags += ['-I' + freetype_include, '-I' + os.path.join(freetype_include, 'config')]