xscale arm build bootstrap fails

[Richard Earnshaw]

> libbackend.a(sched-rgn.o)(.text+0x15a0): In function `compute_dom_prob_ps':
> /usr/src/cvs-others/gcc-trees/gcc-head/build-tmp-0/gcc/../../gcc/gcc/sched-rgn.c:1105: undefined reference to `__extendsfdf2'
> libbackend.a(sched-rgn.o)(.text+0x15bc):/usr/src/cvs-others/gcc-trees/gcc-head/build-tmp-0/gcc/../../gcc/gcc/sched-rgn.c:1105: undefined reference to `__extendsfdf2'
> libbackend.a(sched-rgn.o)(.text+0x168c):/usr/src/cvs-others/gcc-trees/gcc-head/build-tmp-0/gcc/../../gcc/gcc/sched-rgn.c:1116: undefined reference to `__extendsfdf2'
> libbackend.a(sched-rgn.o)(.text+0x18b0): In function `compute_trg_info':
> /usr/src/cvs-others/gcc-trees/gcc-head/build-tmp-0/gcc/../../gcc/gcc/sched-rgn.c:1165: undefined reference to `__extendsfdf2'

This is because the extendsfdf2 pattern was renamed to an anonymous 
pattern when support for the Maverick co-processor was added, but no 
expander was added.

Nick, this is a serious regression introduced by the Maverick port.

R.