There's only one <sys/system_properties.h> now.

Change-Id: I4d535484b9e25fda304fb748b7796e513c832265
diff --git a/libcutils/properties.cpp b/libcutils/properties.cpp
index 03f0496..d3a2b50 100644
--- a/libcutils/properties.cpp
+++ b/libcutils/properties.cpp
@@ -93,8 +93,7 @@
 
 #if __has_include(<sys/system_properties.h>)
 
-#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
-#include <sys/_system_properties.h>
+#include <sys/system_properties.h>
 
 struct callback_data {
     void (*callback)(const char* name, const char* value, void* cookie);