frv sibcalls and conditional returns

[Jim Wilson]

Alexandre Oliva wrote:
> This patch arranges for GCC to emit optimal code for syscall wrappers
> in frv-uclinux.  Sibcalls were already implemented, but Richard
> Sandiford says he ran into problems in them a very long time ago,
> which got him to fully disable them in the branch we've been working
> on, to the point that I reimplemented it from scratch.

OK.

frv_function_ok_for_sibcall has no explanatory comment before it.  It 
should also have ATTRIBUTE_UNUSED markers on the parameters to avoid 
compiler warnings.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com