make: mips-linux-g++: Command not found
make: *** [.obj/release-shared-emb-mips/bookdelegate.o] Error 127
You have to search for your cross compiler directory. You might have something called mipsel-linux-g++ or similar instead of mips-linux-g++. You should link the actual g++ to the one that qt is asking you. For example:

you don't have mips-linux-g++ but you have mipsel-linux-g++ then, place where the croos compiler is and:

user@whereeveryouare$ln -s mipsel-linux-g++ mips-linux-g++

bye