Almost obvious, but I'll play it conservative.  ;-)

There were seven, and now eight, places in handle_inferior_event
where a local struct symtab_and_line is declared and used briefly.
One of them even opens and closes a block just for this purpose.

This patch merges those all into a single local temp variable.

They all initialize it, and all but one of them returns after
using it, so they can't interact.  Plus I ran the testsuites
with no regressions.

OK to check in?