Add /system/vendor/odm for VINTF search path

Compared with board_config.mk and found this one is missing.

Also add docs to explain where are these values from.

Test: pass

Change-Id: Ic22d75a538657bd286edcae6d95f9ee462911975
diff --git a/tools/releasetools/check_target_files_vintf.py b/tools/releasetools/check_target_files_vintf.py
index 543147c..a556f53 100755
--- a/tools/releasetools/check_target_files_vintf.py
+++ b/tools/releasetools/check_target_files_vintf.py
@@ -38,11 +38,13 @@
 # paths (VintfObject.cpp).
 # These paths are stored in different directories in target files package, so
 # we have to search for the correct path and tell checkvintf to remap them.
+# Look for TARGET_COPY_OUT_* variables in board_config.mk for possible paths for
+# each partition.
 DIR_SEARCH_PATHS = {
     '/system': ('SYSTEM',),
     '/vendor': ('VENDOR', 'SYSTEM/vendor'),
     '/product': ('PRODUCT', 'SYSTEM/product'),
-    '/odm': ('ODM', 'VENDOR/odm'),
+    '/odm': ('ODM', 'VENDOR/odm', 'SYSTEM/vendor/odm'),
 }
 
 UNZIP_PATTERN = ['META/*', '*/build.prop']