hw-breakpoints: Fix hardware breakpoints -> perf events dependency

The kbuild's select command doesn't propagate through the config
dependencies.

Hence the current rules of hardware breakpoint's config can't
ensure perf can never be disabled under us.

We have:

config X86
	selects HAVE_HW_BREAKPOINTS

config HAVE_HW_BREAKPOINTS
	select PERF_EVENTS

config PERF_EVENTS
	[...]

x86 will select the breakpoints but that won't propagate to perf
events. The user can still disable the latter, but it is
necessary for the breakpoints.

What we need is:

 - x86 selects HAVE_HW_BREAKPOINTS and PERF_EVENTS
 - HAVE_HW_BREAKPOINTS depends on PERF_EVENTS

so that we ensure PERF_EVENTS is enabled and frozen for x86.

This fixes the following kind of build errors:

 In file included from arch/x86/kernel/hw_breakpoint.c:31:
 include/linux/hw_breakpoint.h: In function 'hw_breakpoint_addr':
 include/linux/hw_breakpoint.h:39: error: 'struct perf_event' has no member named 'attr'

v2: Select also ANON_INODES from x86, required for perf
Reported-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Michal Marek <mmarek@suse.cz>
Reported-by: Andrew Randrianasulu <randrik_a@yahoo.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1261010034-7786-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/Kconfig

@@ -135,9 +135,7 @@ config HAVE_DEFAULT_NO_SPIN_MUTEXES
 
 config HAVE_HW_BREAKPOINT
 	bool
-	depends on HAVE_PERF_EVENTS
-	select ANON_INODES
-	select PERF_EVENTS
+	depends on PERF_EVENTS
 
 config HAVE_USER_RETURN_NOTIFIER
 	bool

arch/x86/Kconfig

@@ -50,6 +50,8 @@ config X86
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_LZMA
 	select HAVE_HW_BREAKPOINT
+	select PERF_EVENTS
+	select ANON_INODES
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_USER_RETURN_NOTIFIER