lib2funcs and fpbit both rely on each other

[Eric Fisher]

Hello,

When building Libgcc with new porting gcc, _floatdidf.o failed for
undefined symbol
_floatsidf. I've been told that _floatsidf is in fpbit.c as
_si_to_df.o. Then I modified the libgcc.mk and firstly build fpbit.
But _pack_df.o failed for undefined symbol
_ashldi3.o which is in libgcc2.c. It seems that they are rely on both
each other.

Thanks again.

Eric