strub: sparc: omit frame in strub_leave [PR112917]

strub: sparc: omit frame in strub_leave [PR112917]

If we allow __strub_leave to allocate a frame on sparc, it will
overlap with a lot of the stack range we're supposed to scrub, because
of the large fixed-size outgoing args and register save area.
Unfortunately, setting up the PIC register seems to prevent the frame
pointer from being omitted.

Since the strub runtime doesn't issue calls or use global variables,
at least on sparc, disabling PIC to compile strub.c seems to do the
right thing.

for  libgcc/ChangeLog

	PR middle-end/112917
	* config.host (sparc, sparc64): Enable...
	* config/sparc/t-sparc: ... this new fragment.