RFC: set "--enable-newlib-hw-fp" according to specific version multilib

[Can Finner]

Hi,
currently --enable-newlib-hw-fp option is disabled by default, but I
want to enable it when compiling specific version multlib.
For example, when compiling multilib for arm cortex-M processors, only
cortex-M4 has fpu, we want have this option enabled
for M4 and disabled for others.

I am going to handle this in configure.host by checking multilib flags
and hopefully work out a patch.

So what's your opinion? Any tips?

Thanks very much.

-- 
Regards.