perf record: Fix branch_stack type in perf_record_opts

The attr.branch_sample_type field is defined as u64 by the API.  As
such, we need to ensure the variable holding the value of the branch
stack filters is also u64 otherwise we may lose bits in the future.

Note also that the bogus definition of the field in perf_record_opts
caused problems on big-endian PPC systems.  Thanks to Anshuman Khandual
for tracking the problem on PPC.
Reported-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NStephane Eranian <eranian@google.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120525211344.GA7729@quadSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf.h

@@ -227,7 +227,7 @@ struct perf_record_opts {
 	unsigned int freq;
 	unsigned int mmap_pages;
 	unsigned int user_freq;
-	int	     branch_stack;
+	u64          branch_stack;
 	u64	     default_interval;
 	u64	     user_interval;
 };