Avoid generating cdex for dex files with duplicate methods

For the cases where two different method have the same code item or
debug info, avoid generating cdex and write the input dex into the
oat file isntead.

Test: test-art-host-gtest
Bug: 72997076
Bug: 72100771
Bug: 72100668
Bug: 63756964

Change-Id: I5dfe2b47b2c908921c8421367536c2d950186ac6