bionic: libc: Added path to root ramdisk build properties file.

Change-Id: Id850e4e5ef4e91cea7ad53f6858886daf660eeec
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 0349e4c..44fe991 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -50,7 +50,7 @@
 
 __BEGIN_DECLS
 
-struct prop_msg 
+struct prop_msg
 {
     unsigned cmd;
     char name[PROP_NAME_MAX];
@@ -58,7 +58,7 @@
 };
 
 #define PROP_MSG_SETPROP 1
-    
+
 /*
 ** Rules:
 **
@@ -82,6 +82,7 @@
 #define PROP_PATH_SYSTEM_BUILD     "/system/build.prop"
 #define PROP_PATH_SYSTEM_DEFAULT   "/system/default.prop"
 #define PROP_PATH_VENDOR_BUILD     "/vendor/build.prop"
+#define PROP_PATH_BOOTIMAGE_BUILD  "/build.prop"
 #define PROP_PATH_LOCAL_OVERRIDE   "/data/local.prop"
 #define PROP_PATH_FACTORY          "/factory/factory.prop"