Remove wxUSE_WCHAR_T, it must always be 1 anyhow

This is not really an option as building requires it to be 1, so don't
make it one in setup.h/configure/cmake and just hardcode it as 1 for
compatibility.

Closes #18558.

build/cmake/init.cmake

@@ -194,9 +194,6 @@ endif()
 
 # Constants for setup.h creation
 set(wxUSE_STD_DEFAULT ON)
-if(wxUSE_UNICODE)
-    set(wxUSE_WCHAR_T ON)
-endif()
 if(NOT wxUSE_EXPAT)
     set(wxUSE_XRC OFF)
 endif()

build/cmake/setup.h.in

@@ -182,8 +182,6 @@
     #cmakedefine01 wxUSE_UNICODE
 #endif
 
-#cmakedefine01 wxUSE_WCHAR_T
-
 
 #cmakedefine01 wxUSE_EXCEPTIONS