perf bench: Use named initializers in the trailer too

perf bench: Use named initializers in the trailer too

To avoid this splat with gcc 4.4.7:

  cc1: warnings being treated as errors
  bench/mem-functions.c:273: error: missing initializer
  bench/mem-functions.c:273: error: (near initialization for ‘memcpy_functions[4].desc’)
  bench/mem-functions.c:366: error: missing initializer
  bench/mem-functions.c:366: error: (near initialization for ‘memset_functions[4].desc’)

Cc: David Ahern <dsahern@gmail.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-0s8o6tgw1pdwvdv02llb9tkd@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>