perf tools: Fix build on gcc 4.4.7

[acme@sandy linux]$ gcc --version
gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-3)
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[acme@sandy linux]$ make O=/tmp/build/perf -C tools/perf install-bin
<SNIP>
  CC       /tmp/build/perf/builtin-trace.o
builtin-trace.c: In function ‘perf_evlist__add_pgfault’:
builtin-trace.c:1997: error: unknown field ‘sample_period’ specified in initializer
make[1]: *** [/tmp/build/perf/builtin-trace.o] Error 1
make: *** [install-bin] Error 2
make: Leaving directory `/home/acme/git/linux/tools/perf'
[acme@sandy linux]$ make O=/tmp/build/perf -C tools/perf install-bin
make O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory `/home/acme/git/linux/tools/perf'

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-qt7h2g5fcf42qiw5hv7mgpjk@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -1994,10 +1994,10 @@ static int perf_evlist__add_pgfault(struct perf_evlist *evlist,
 	struct perf_event_attr attr = {
 		.type = PERF_TYPE_SOFTWARE,
 		.mmap_data = 1,
-		.sample_period = 1,
 	};
 
 	attr.config = config;
+	attr.sample_period = 1;
 
 	event_attr_init(&attr);