bionic: libc: Added path to vendor build properties file.

Signed-off-by: Daniel Rosenberg <drosen@google.com>

(cherry picked from commit 71d220c1de1372e20c8bbec4ccf387991a3bb549)

Bug: 18281574
Change-Id: I2843f23ecb4c4ca79b230d8041bbca02dbedeadc
diff --git a/libc/include/sys/_system_properties.h b/libc/include/sys/_system_properties.h
index 5a681df..0349e4c 100644
--- a/libc/include/sys/_system_properties.h
+++ b/libc/include/sys/_system_properties.h
@@ -81,6 +81,7 @@
 #define PROP_PATH_RAMDISK_DEFAULT  "/default.prop"
 #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_LOCAL_OVERRIDE   "/data/local.prop"
 #define PROP_PATH_FACTORY          "/factory/factory.prop"