Add a CleanSpec for mockito.
Add a CleanSpec for mockito.

A recent change (I2a162a62540558e29617e6a965fd6b0b68ca3b3b) has updated
the way mockito-api is built, so we need to clean that target.

Change-Id: I0ced9e47192cd6c91bd9dee2483cb3b4f09228b3

xin3liang/platform_external_mockito,thiz11/platform_external_mockito,xin3liang/platform_external_mockito,android-ia/platform_external_mockito,Omegaphora/external_mockito,geekboxzone/lollipop_external_mockito,Omegaphora/external_mockito,geekboxzone/mmallow_external_mockito,IllusionRom-deprecated/android_platform_external_mockito,geekboxzone/lollipop_external_mockito,IllusionRom-deprecated/android_platform_external_mockito,android-ia/platform_external_mockito,geekboxzone/mmallow_external_mockito,MIPS/external-mockito,yinquan529/platform-external-mockito,thiz11/platform_external_mockito,Omegaphora/external_mockito,geekboxzone/mmallow_external_mockito,android-ia/platform_external_mockito,MIPS/external-mockito,yinquan529/platform-external-mockito,yinquan529/platform-external-mockito,geekboxzone/lollipop_external_mockito