v850 and rl78 failed to build newlib with an ICE.  I've also got a 
report from an ARM automated tester that looks like the same underlying 
problem.


Basically we need to check if simple_return and return insns are 
available before trying to use them.


Bootstrapped on x86_64 (regression testing in progress). Verified this 
fixes the v850 and rl78 build failures.   Installing on the trunk 
momentarily.


Jeff