Bug : -DBUILD_CONFIG=mysql_release sets SIGNCODE parameter which requires 
singtool.exe (part of Windows SDK)  in order to be able to sign the binaries (
only if valid certificate is found). However singtool is not a part of the SDK shipped
with Visual Studio Express, so the build fails claiming missing singtools.exe

Fix: Do not  use SIGNCODE  wiith VC Express.

Also, fix broken nmake build (*.rc files could not be compiled due to ADD_DEFINITIONS
contaning C/C++ compiler specific flags)