kernel: add c++ support

include/socks/percpu.h

@@ -4,6 +4,10 @@
 #include <socks/status.h>
 #include <socks/compiler.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define DEFINE_PERCPU_VAR(type, name) \
 	__section(".data.percpu") type name
 
@@ -14,4 +18,8 @@
 extern kern_status_t init_per_cpu_areas(void);
 extern void *__percpu_get(void *var);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif