Hi Genode Community

I'm preparing a port file for WebToolkit library. I have prepared the basic file to download the library, extract the source code and generate include files.
I have an small problem with this library. This library is written in C++, but source files have .C extension. This library must be compiled with Qt support and .C files are recognized as C source file not C++. I need rename all .C files to .cpp. This can be done manually with this command line on the WebToolkit's source folder:
find . -name "*.C" -exec rename 's/\.C$/.cpp/' '{}' \;
I have tried something like this on the port file:
LICENSE   := GPLv2
VERSION   := 3.3.5-rc2
DOWNLOADS := wt.archive
...
CMD := `find . -name "*.C" -exec rename 's/\.C$/.cpp/' '{}' \;`

default:
    ${CMD}
But when prepare the port this not work. It give me this output:
...
Substitution replacement not terminated at (user-supplied code).
...
Somebody have any suggestion or any idea about how can i do this automatically on the port file?

Best regards

-- 
Lic. Reinier Millo Sánchez
Centro de Estudios de Informática
Universidad Central "Marta Abreu" de Las Villas
Carretera a Camajuaní Km 5 1/2
Santa Clara, Villa Clara, Cuba
CP 54830

"antes de discutir ... respira;
  antes de hablar ... escucha;
 antes de escribir ... piensa;
  antes de herir ... siente;
 antes de rendirte ... intenta;
  antes de morir ... vive"