OSX install (10.8) GDC build fails

[Daniel Harper]

I'm having trouble building GDC (taken from the gdc-4.7 branch on 
github) using gcc-4.7.1

After about 10-15 minutes it just bails out with this error

/Users/danielharper/gdc/objdir/./gcc/xgcc 
-B/Users/danielharper/gdc/objdir/./gcc/ 
-B/opt/gdc/i386-apple-darwin12.1.0/bin/ 
-B/opt/gdc/i386-apple-darwin12.1.0/lib/ -isystem 
/opt/gdc/i386-apple-darwin12.1.0/include -isystem 
/opt/gdc/i386-apple-darwin12.1.0/sys-include    -o zlib/uncompr.o 
-DHAVE_CONFIG_H -I . -I ../../../../gcc-4.7.1/libphobos/gcc 
-I../../../../gcc-4.7.1/libphobos/../zlib -g -O2  -m64 -c 
../../../../gcc-4.7.1/libphobos/../zlib/uncompr.c
make[8]: *** No rule to make target `libdruntime/libgdruntime.a', 
needed by `libgphobos2.a'.  Stop.
make[8]: *** Waiting for unfinished jobs....
/Users/danielharper/gdc/objdir/./gcc/xgcc 
-B/Users/danielharper/gdc/objdir/./gcc/ 
-B/opt/gdc/i386-apple-darwin12.1.0/bin/ 
-B/opt/gdc/i386-apple-darwin12.1.0/lib/ -isystem 
/opt/gdc/i386-apple-darwin12.1.0/include -isystem 
/opt/gdc/i386-apple-darwin12.1.0/sys-include    -o zlib/zutil.o 
-DHAVE_CONFIG_H -I . -I ../../../../gcc-4.7.1/libphobos/gcc 
-I../../../../gcc-4.7.1/libphobos/../zlib -g -O2  -m64 -c 
../../../../gcc-4.7.1/libphobos/../zlib/zutil.c
make[7]: *** [all-recursive] Error 1
make[6]: *** [all] Error 2
make[5]: *** [multi-do] Error 1
make[4]: *** [all-multi] Error 2
make[3]: *** [all-recursive] Error 1
make[2]: *** [all] Error 2
make[1]: *** [all-target-libphobos] Error 2
make: *** [all] Error 2

I'm not sure where to go from here, can anyone help?