CMake/ninja error?

I’m having trouble with Cmake and the produced ninja “make-files”
All seems to go well with “Cmake -GNinja”, but the commands to
produce a .res file is wrong. It includes a “/MP” E.g. if I do a
‘ninja.exe gnuradio-runtime’, which gives:

[1/2] Building RC object
FAILED: “G:/MingW32/bin/CMake/bin/cmcldeps.exe” RC … /MP /bigobj


fatal error RC1106: invalid option: /MP
ninja: build stopped: subcommand failed.

Not sure if this is the fault of Cmake, Ninja or GnuRadio.