D20509: Detect duplicate ANDROID_EXTRA_LIBS and minor bug fix

[Sharaf Zaman]

sh-zam marked 2 inline comments as done.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D20509

To: sh-zam, apol, vkrause
Cc: kde-buildsystem, kde-frameworks-devel, bencreasy, michaelh, ngraham, bruns