gltfpack: Switch from manual UTF8 conversion to a manifest

Since CMake supports manifest files as sources, it's a little easier to
specify UTF-8 as the ANSI encoding via that; this is embedded into .exe
and is used for command line arguments as well so the rest of the code
just works.

CMakeLists.txt

@@ -58,6 +58,10 @@ set(GLTF_SOURCES
     gltf/write.cpp
 )
 
+if(WIN32)
+    list(APPEND GLTF_SOURCES gltf/gltfpack.manifest)
+endif()
+
 if(MSVC)
     add_compile_options(/W4)
 else()

gltf/gltfpack.cpp

@@ -1217,8 +1217,12 @@ unsigned int textureMask(const char* arg)
 }
 
 #ifndef GLTFFUZZ
-int run(int argc, char** argv)
+int main(int argc, char** argv)
 {
+#if !defined(__wasi__)
+	setlocale(LC_ALL, "C"); // disable locale specific convention for number parsing/printing
+#endif
+
 	meshopt_encodeVertexVersion(0);
 	meshopt_encodeIndexVersion(1);
 
@@ -1629,43 +1633,12 @@ int run(int argc, char** argv)
 }
 #endif
 
-#if !defined(_WIN32) && !defined(__wasi__)
-int main(int argc, char** argv)
-{
-	setlocale(LC_ALL, "C"); // disable locale specific convention for number parsing/printing
-	return run(argc, argv);
-}
-#endif
-
-#ifdef _WIN32
-int wmain(int argc, wchar_t* argv[])
-{
-	setlocale(LC_ALL, "en_us.utf8"); // use utf8 as ansi codepage
-
-	std::vector<char*> args;
-	for (int i = 0; i < argc; ++i)
-	{
-		std::mbstate_t state = {};
-		const wchar_t* argw = argv[i];
-		size_t len = wcsrtombs(NULL, &argw, 0, &state);
-		if (len == size_t(-1))
-			return -1;
-
-		char* argu = new char[len + 1];
-		wcsrtombs(argu, &argw, len + 1, &state);
-		args.push_back(argu);
-	}
-
-	return run(int(args.size()), args.data());
-}
-#endif
-
 #ifdef __wasi__
 extern "C" int pack(int argc, char** argv)
 {
 	chdir("/gltfpack-$pwd");
 
-	int result = run(argc, argv);
+	int result = main(argc, argv);
 	fflush(NULL);
 	return result;
 }

gltf/gltfpack.manifest

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity type="win32" name="..." version="6.0.0.0"/>
+  <application>
+    <windowsSettings>
+      <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
+    </windowsSettings>
+  </application>
+</assembly>