opencascade*: fix build after mesa update

pkgs/development/libraries/opencascade/6.5.nix

···
 
   # -fpermissive helps building opencascade, although gcc detects a flaw in the code
   # and reports an error otherwise. Further versions may fix that.
-  NIX_CFLAGS_COMPILE = "-fpermissive";
+  NIX_CFLAGS_COMPILE = "-fpermissive"
+  # https://bugs.freedesktop.org/show_bug.cgi?id=83631
+    + " -DGLX_GLXEXT_LEGACY";
 
   configureFlags = [ "--with-tcl=${tcl}/lib" "--with-tk=${tk}/lib" "--with-qt=${qt4}" "--with-ftgl=${ftgl}" "--with-freetype=${freetype}" ];
 

pkgs/development/libraries/opencascade/default.nix

···
     cmakeFlags="$cmakeFlags -DINSTALL_DIR=$out -D3RDPARTY_TCL_DIR=${tcl} -D3RDPARTY_FREETYPE_DIR=${freetype}"
   '';
 
+  # https://bugs.freedesktop.org/show_bug.cgi?id=83631
+  NIX_CFLAGS_COMPILE = "-DGLX_GLXEXT_LEGACY";
+
   postInstall = ''
     mv $out/inc $out/include
     mkdir -p $out/share/doc/${name}

pkgs/development/libraries/opencascade/oce.nix

···
     cmakeFlags="$cmakeFlags -DOCE_INSTALL_PREFIX=$out"
   '';
 
+  # https://bugs.freedesktop.org/show_bug.cgi?id=83631
+  NIX_CFLAGS_COMPILE = "-DGLX_GLXEXT_LEGACY";
+
   enableParallelBuilding = true;
 
   meta = {