QNX 6.4.1 IDE 4.6 Windows host

Customer reported, and I reproduced that if you follow the IDE doc instructions for 'Creating the equivalent of a make 
project' and set the 'Generate Makefiles automatically' option like it says, the resulting makefile starts:

################################################################################
# Automatically-generated file. Do not edit!
################################################################################
"
-include ../makefile.init

RM := del
[snip]
"

If you run a 'make clean', it fails to find 'del' :
"

**** Clean-only build of configuration QNX QCC for project testmake ****

make clean 
del  ./testmake.d  testmake
process_begin: CreateProcess(NULL, del ./testmake.d testmake, ...) failed.
make (e=2): The system cannot find the file specified.

make: [clean] Error 2 (ignored)
"

Known issue ? Any workaround ?

Thanks

Dave