Force GHC to pass defines to C++

Author: dpwiz

dear-imgui.cabal

@@ -202,11 +202,14 @@ library
       -optcxx-std=c++11
 
   if flag(disable-obsolete)
+    ghc-options: -optcxx-DIMGUI_DISABLE_OBSOLETE_FUNCTIONS
     cxx-options: -DIMGUI_DISABLE_OBSOLETE_FUNCTIONS
 
   if flag(use-wchar32)
     cxx-options: -DIMGUI_USE_WCHAR32
     cpp-options: -DIMGUI_USE_WCHAR32
+    if impl(ghc >= 9.10)
+      ghc-options: -optcxx-DIMGUI_USE_WCHAR32
 
   if flag(use-ImDrawIdx32)
     cxx-options: "-DImDrawIdx=unsigned int"