How to disable GCC parallel compilation of universal binaries?

I know it's a useful feature since I have a core duo processor, but I'm 
compiling quite heavy C++ sources and my machine has not enough memory 
to keep TWO instances of GCC compiling them in memory at once..

I ran through configure/make command line, and I have configured with 
CXXFLAGS and LDFLAGS:

-arch i386 -arch ppc


There is some other flag that let you tell GCC not to compile the two 
archs at the same time?

Bye,
  Gabry