It shows up as a failure to compile libiberty with the stage1 compiler
during stage2, because of the warning you added causing configure
tests to fail
configure:3801: /Users/dannyb/gccstuff/pta-dev/build/./prev-gcc/xgcc
-B/Users/dannyb/gccstuff/pta-dev/build/./prev-gcc/
-B/usr/local/i386-apple-darwin9.0.0b1/bin/ -E conftest.c
conftest.c:0: warning: variable tracking requested, but useless unless
producing debug info
configure:3807: $? = 0
This is because you turn it on unconditionally in darwin.c for 10.5+,
so it warns even when we are not going to output code.
Please fix by not forcing it on unless -g is passed, so the warning
does not happen.