Eclipse: Configure classpath to ignore warnings in generated classes
Eclipse: Configure classpath to ignore warnings in generated classes

The auto library sometimes generates code that causes warnings in
Eclipse. See [1] and [2] for example.

Those warnings can be suppressed by configuring the Eclipse project
as described in [3]. However, because that configuration is stored in
the .classpath file it is lost every time the project is regenerated,
which can be quite frequent when switching between branches.

Modify the classpath generation to explicitly include the settings
that are added by the manual step in [3]. This means that the settings
are persisted even after regenerating the project.

[1] https://github.com/google/auto/issues/725
[2] https://github.com/google/auto/issues/731
[3] https://github.com/google/auto/issues/725#issuecomment-485056751

Change-Id: Ieeaab014aa1d04293e66e88c7ce9f2fd9e24e9c4

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