hw-breakpoints: Fix build on !perf architectures

the arch/alpha build fails with:

 In file included from tip/kernel/exit.c:52:
 tip/include/linux/hw_breakpoint.h: In function 'hw_breakpoint_addr':
 tip/include/linux/hw_breakpoint.h:21: error: 'struct perf_event' has no member named 'attr'
 [...]

Move these helper inlines inside the CONFIG_HAVE_HW_BREAKPOINT ifdef.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1258114575-32655-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/hw_breakpoint.h

@@ -16,6 +16,8 @@ enum {
 	HW_BREAKPOINT_X = 4,
 };
 
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+
 static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
 {
 	return bp->attr.bp_addr;
@@ -31,7 +33,6 @@ static inline int hw_breakpoint_len(struct perf_event *bp)
 	return bp->attr.bp_len;
 }
 
-#ifdef CONFIG_HAVE_HW_BREAKPOINT
 extern struct perf_event *
 register_user_hw_breakpoint(unsigned long addr,
 			    int len,