perlPackages.{Wx,WxGLCanvas}: fix build failure (#459913)

pkgs/top-level/perl-packages.nix

@@ -38203,6 +38203,10 @@ with self;
       substituteInPlace ext/dnd/XS/DataObject.xs \
         --replace "#ifdef __WXGTK20__" "#if wxUSE_GUI"
     '';
+    # Build system attempts to compile c++ files with clang.
+    preConfigure = ''
+      export CC=$CXX
+    '';
     propagatedBuildInputs = [ AlienWxWidgets ];
     # Testing requires an X server:
     #   Error: Unable to initialize GTK, is DISPLAY set properly?"
@@ -38228,6 +38232,10 @@ with self;
       pkgs.libGLU
       Wx
     ];
+    # Build system attempts to compile c++ files with clang.
+    preConfigure = ''
+      export CC=$CXX
+    '';
     doCheck = false;
     meta = {
       description = "wxPerl demo helper for Wx::GLCanvas";