Compilation Errors of Mozilla Firefox

What is going on? I'm trying to build an optimization build of Mozilla Firefox in Mac OS X 10.3.8 for Apple iBook G4, but there is always a error in source codes. The error is ``jsopcode.c:366: error: Va_start' used in function with fixed args'', and gcc printed out the same error about 20-30 times. I don't know how to solve this problem. The source code of Firefox 1.0.1 was downloaded form And I just add many optimization flags as possible for PowerPC G4 7450.

-O3 -faltivec -mcpu=7450 -mtune=7450 -mpowerpc -mpowerpc-gfxopt -mpowerpc-gpopt -ffast-math -funroll-loops -fsched-interblock -falign-loops=16 -falign-jumps=16 -falign-functions=16 -falign-jumps-max-skip=15 -falign-loops-max-skip=15