Remove setlocale call in __hxcpp_stdlibs_boot (#1284)

On Windows, this meant the utf-8 string passed to printf("%s") was
interpreted as if it is from the default system locale encoding instead
of utf-8, which are incompatible so any non-ASCII text comes out
garbled. This setlocale call also meant that using `chcp 65001` does not
haxe the correct effect of being able to view the full range of utf-8
characters from print output.

Originally, this setlocale call was required required due to the use of
print("%S"), but the printing functions in Stdlibs.cpp no longer rely on
that so it is safe to remove.

Author: tobil4sk

src/hx/StdLibs.cpp

@@ -283,8 +283,6 @@ void __hxcpp_stdlibs_boot()
    //_setmode(_fileno(stdin), 0x00040000); // _O_U8TEXT
    #endif
 
-   // This is necessary for UTF-8 output to work correctly.
-   setlocale(LC_ALL, "");
    setlocale(LC_NUMERIC, "C");
 
    // I think this does more harm than good.