Use the basename of file_contexts from the info dict.

Changes in [1] break the backward compatibility of the OTA scripts. Fix
the issue by extracting the file basename from the info dict in
META/misc_info.txt.

[1] commit d3a803e6680e86f7b4960d51ab0b620728b793ca

Bug: 23620049
Change-Id: I40a5625bbe0beb295f34b2328906a4a4283fe59b
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index d56c0fd..0678a13 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -159,11 +159,12 @@
     # to build images than the one running on device, such as when enabling
     # system_root_image. In that case, we must have the one for image
     # generation copied to META/.
-    fc_config = os.path.join(input_dir, "META", "file_contexts.bin")
+    fc_basename = os.path.basename(d.get("selinux_fc", "file_contexts"))
+    fc_config = os.path.join(input_dir, "META", fc_basename)
     if d.get("system_root_image") == "true":
       assert os.path.exists(fc_config)
     if not os.path.exists(fc_config):
-      fc_config = os.path.join(input_dir, "BOOT", "RAMDISK", "file_contexts.bin")
+      fc_config = os.path.join(input_dir, "BOOT", "RAMDISK", fc_basename)
       if not os.path.exists(fc_config):
         fc_config = None