remove rootdir build.prop

merge with default.prop

Change-Id: I6cff4527dec2b31bdde42ec26c42ef2782f8deb4
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 8086020..a0315b5 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -81,7 +81,6 @@
 #define PROP_PATH_RAMDISK_DEFAULT  "/default.prop"
 #define PROP_PATH_SYSTEM_BUILD     "/system/build.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"