QmlDebuggingHelper library not built for gcce

For compiling the debugging helpers we choose the configuration for the first toolchain.
Problems:

• qmake might e.g. not create rules for gcce if this isn't the toolchain, but just for winscw, arm5, armv6
• 'make all' will stop at the first problem because e.g. armv5 toolchain is not properly set up, and ignore gcce