Support /product partition

This CL will enable reading /product/build.prop and add product paths
into ld.config.txt.in.

Bug: 64195575
Test: tested with 'PRODUCT_PRODUCT_PROPERTIES := ro.product.abc=abc' on
sailfish

Change-Id: Ie996def20e25dc1afe0c74af2096af844934b2dc
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index ca992d6..d8163ab 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -88,6 +88,11 @@
 else
   LOCAL_POST_INSTALL_CMD += ; ln -sf /system/vendor $(TARGET_ROOT_OUT)/vendor
 endif
+ifdef BOARD_USES_PRODUCTIMAGE
+  LOCAL_POST_INSTALL_CMD += ; mkdir -p $(TARGET_ROOT_OUT)/product
+else
+  LOCAL_POST_INSTALL_CMD += ; ln -sf /system/product $(TARGET_ROOT_OUT)/product
+endif
 ifdef BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
   LOCAL_POST_INSTALL_CMD += ; mkdir -p $(TARGET_ROOT_OUT)/cache
 else