[Bug rtl-optimization/66845] one more %si register function clobbering issue

[marcus at jet dot franken.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66845

--- Comment #2 from marcus at jet dot franken.de ---
compiler used is gcc version 5.1.1 20150707 [gcc-5-branch revision 225501]
(SUSE Linux) with the patch from bug 66782 applied.