bugfix: config c++17 to workaround constexpr issue on macos(clang

- https://forum.d2learn.org/topic/145
- https://github.com/llvm/llvm-project/blob/06fc87bcd3d61a08f8c035e60949631f61bccee7/libcxx/include/array#L61

Signed-off-by: sunrisepeak <speakshen@163.com>

Author: Sunrisepeak

dslings/cpp11/xmake.lua

@@ -90,6 +90,7 @@ target("cpp11-07-constexpr-1")
 -- target: cpp11-08-literal-type
 
 target("cpp11-08-literal-type-0")
+    set_languages("c++17") -- TODO: optimize it
     add_files("08-literal-type-0.cpp")
 
 target("cpp11-08-literal-type-1")