Fix <sys/epoll.h> and <sys/system_properties.h> to include proper C++ inclusion guards

libc/include/sys/system_properties.h

@@ -29,6 +29,10 @@
 #ifndef _INCLUDE_SYS_SYSTEM_PROPERTIES_H
 #define _INCLUDE_SYS_SYSTEM_PROPERTIES_H
 
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
 typedef struct prop_info prop_info;
 
 #define PROP_NAME_MAX   32
@@ -76,4 +80,6 @@ int __system_property_read(const prop_info *pi, char *name, char *value);
 */ 
 const prop_info *__system_property_find_nth(unsigned n);
 
+__END_DECLS
+
 #endif