[Bug target/44995] define a macro for presence of -mregnames option

[fche at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44995

--- Comment #4 from Frank Ch. Eigler <fche at redhat dot com> 2011-08-19 11:24:19 UTC ---
We have worked around this powerpc oddity in systemtap's recent sdt.h
versions by using both %0 and %I0 together to get a special markup for
literals vs. register names.