hw-breakpoints: Provide an off-case for counter_arch_bp()

If an arch doesn't support the hw breakpoints, counter_arch_bp()
has no off case to cover the missing breakpoint info structure
from the perf event. The result is a build error in non-x86
configs.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: 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>
Cc: Prasad <prasad@linux.vnet.ibm.com>

include/linux/hw_breakpoint.h

@@ -16,11 +16,6 @@ enum {
 	HW_BREAKPOINT_X = 4,
 };
 
-static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
-{
-	return &bp->hw.info;
-}
-
 static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
 {
 	return bp->attr.bp_addr;
@@ -83,6 +78,11 @@ extern void release_bp_slot(struct perf_event *bp);
 
 extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
 
+static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
+{
+	return &bp->hw.info;
+}
+
 #else /* !CONFIG_HAVE_HW_BREAKPOINT */
 
 static inline struct perf_event *
@@ -126,6 +126,11 @@ static inline void release_bp_slot(struct perf_event *bp) 		{ }
 
 static inline void flush_ptrace_hw_breakpoint(struct task_struct *tsk)	{ }
 
+static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
 #endif /* _LINUX_HW_BREAKPOINT_H */