perf probe: Fix compiles due to declarations using perf_probe_point

perf probe: Fix compiles due to declarations using perf_probe_point

perf fails to build with gcc "(GCC) 4.4.7 20120313 (Red Hat
4.4.7-4.0.9)" (a.k.a., RHEL6 / CentOS 6 / OL 6):

  cc1: warnings being treated as errors
  util/probe-event.c: In function ‘get_alternative_line_range’:
  util/probe-event.c:359: error: missing initializer
  util/probe-event.c:359: error: (near initialization for ‘pp.file’)
  util/probe-event.c:359: error: missing initializer
  util/probe-event.c:359: error: (near initialization for ‘result.function’)

Fix by bringing in initializers to declaration.

Signed-off-by: David Ahern <david.ahern@oracle.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/1426084580-60780-1-git-send-email-david.ahern@oracle.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>