Add some missing unittests to unittests.gypi.
Add some missing unittests to unittests.gypi.

I'm not sure about experimental/pdb_writer/pdb_writer.gyp:pdb_writer_unittests ,

but right now we're running it on the coverage bot, so we should either
add it to this list or stop running it on the coverage bot ?

Review URL: https://codereview.chromium.org/1872253003

google/syzygy,Eloston/syzygy,Eloston/syzygy,google/syzygy,google/syzygy,google/syzygy