i*86-*-linux* xfails for "backtrace through signal handler". * gdb.base/corefile.exp: Add i*86-*-sysv4* xfail for "print func2::coremaker_local". * gdb.base/break.exp: Add i*86-*-sysv4*, sparc-sun-sunos4, xfail for "delete all breakpoints when none".