Supersize: Fix failures when passing an elf file from secondary abis.

For secondary abis the thinlto-cache directory is a sub-directory of
the secondary abi directory.

Change-Id: I1a87df0aec52f0550efa203be3ff0abb00a770d3
Reviewed-on: https://chromium-review.googlesource.com/c/1349852Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611254}

tools/binary_size/libsupersize/linker_map_parser.py

@@ -413,7 +413,7 @@ class MapFileParserLld(object):
             else:
               # e.g. <internal>:(.text.thunk)
               sym_maker.cur_sym.full_name = '** ' + mangled_name
-          elif cur_obj == 'lto.tmp' or cur_obj.startswith('thinlto-cache'):
+          elif cur_obj == 'lto.tmp' or 'thinlto-cache' in cur_obj:
             pass
           else:
             sym_maker.cur_sym.object_path = cur_obj