x86, bts: reenable ptrace branch trace support

The races found by Oleg Nesterov have been fixed.

Reenable branch trace support.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <20090424094448.A30216@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig.cpu

@@ -506,7 +506,6 @@ config X86_PTRACE_BTS
 	bool "Branch Trace Store"
 	default y
 	depends on X86_DEBUGCTLMSR
-	depends on BROKEN
 	---help---
 	  This adds a ptrace interface to the hardware's branch trace store.