Fixes for tools/coverage.sh
Fixes for tools/coverage.sh

* add '-mindepth 1' to the 'find' command that is used to get the plugin
  list:
  Without this parameter the result contains "plugins/" in addition to
  "plugins/<plugin-1>", "plugins/<plugin-2", etc.
* fix copy command to copy plugin sources:
  We used "cp -r plugins/*/{java,javatests}/* ${destdir}/${plugin}/java"
  which copied the code of all plugins into each plugin folder at the
  destination. To fix this include the plugin name into the source
  folder, so that only code of this one plugin is copied. If we do this
  we should test if the source folder exists before copying to avoid
  error messages for non-existing folder.

Signed-off-by: Edwin Kempin <d43fb6c98c97e553b671ed9a9318100f1de386e7@google.com>
Change-Id: I338b99209eff5643a83e401e2a56ac3113cbe541

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