With newlib's default compiler flags(-O2 and whatnot),
the GCC I'm using creates calls to __aeabi_(f|d)div.
This causes a little extra register copying
and an unnecessary branch.

Additionally, __aeabi_?div may throw exceptions,
which is probably not what we want a
simple assignment to do.

Compiler version tested:
arm-none-eabi-gcc (15:5.4.1+svn241155-1) 5.4.1 20160919

-Richard