Some ppc fixes for #4115, patch by kallisti5 (without the #ifdef _BOOT_MODE):

- stubbed out arch_cpu_init_percpu(),
- make atomic ops declarations extern "C",
- move calls to [i]sync inside the asm code that needs it.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32067 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/user_atomic.h

@@ -9,6 +9,10 @@
  * in userspace, they are implemented as these syscalls.
  */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int32 _user_atomic_set(vint32 *value, int32 newValue);
 int32 _user_atomic_test_and_set(vint32 *value, int32 newValue, int32 testAgainst);
 int32 _user_atomic_add(vint32 *value, int32 addValue);
@@ -23,4 +27,9 @@ int64 _user_atomic_and64(vint64 *value, int64 andValue);
 int64 _user_atomic_or64(vint64 *value, int64 orValue);	
 int64 _user_atomic_get64(vint64 *value);
 
+#ifdef __cplusplus
+}
+#endif
+
+
 #endif	/* _KERNEL_USER_ATOMIC_H */