x11-toolkits/mygui: fix build with libc++ 19
As noted in the libc++ 19 release notes [1], std::char_traits<> is now
only provided for char, char8_t, char16_t, char32_t and wchar_t, and any
instantiation for other types will fail.
This causes x11-toolkits/mygui to fail to compile with clang 19 and
libc++ 19, resulting in errors similar to:
In file included from /wrkdirs/usr/ports/x11-toolkits/mygui/work/mygui-MyGUI3.4.2/MyGUIEngine/include/MyGUI_Common.h:12:
/usr/include/c++/v1/string:820:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned short>'
820 | static_assert(is_same<_CharT, typename traits_type::char_type>::value,
y | ^
/wrkdirs/usr/ports/x11-toolkits/mygui/work/mygui-MyGUI3.4.2/MyGUIEngine/include/MyGUI_UString.h:213:4: note: in instantiation of template class 'std::basic_string<unsigned short>' requested here
213 | dstring::iterator mIter;
| ^
/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
| ^These can be fixed by using char16_t instead of uint16_t for the
code_point type, and char32_t instead of uint32_t for the
unicode_char type.
[1] https://libcxx.llvm.org/ReleaseNotes/19.html#deprecations-and-removals
PR: 281974
Approved by: maintainer timeout (2 weeks)
MFH: 2024Q4
(cherry picked from commit 2e294149c6682f1a8cb384d0e36a14b12b9c3e35)