perf tools: Simplify die() mechanism

This should die altogether, but for now lets remove a bit of this stuff,
as it is not used at all.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ade3n99xscldhg5mx2vzd8p3@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/util.h

@@ -140,7 +140,6 @@ extern void warning(const char *err, ...) __attribute__((format (printf, 1, 2)))
 
 #include "../../../include/linux/stringify.h"
 
-extern void set_die_routine(void (*routine)(const char *err, va_list params) NORETURN);
 extern void set_warning_routine(void (*routine)(const char *err, va_list params));
 
 extern int prefixcmp(const char *str, const char *prefix);