clients/android: add clean target

[nor...@perkeep.org]

https://github.com/perkeep/perkeep/commit/14ac3dd571485e6470c70b7f25edddb17b871b24

commit 14ac3dd571485e6470c70b7f25edddb17b871b24
Author: Sebastien Binet <bi...@cern.ch>
Date: Wed Jun 1 14:02:46 2022 +0200

clients/android: add clean target

Signed-off-by: Sebastien Binet <bi...@cern.ch>

diff --git a/clients/android/Makefile b/clients/android/Makefile
index 20dce85..97387ac 100644
--- a/clients/android/Makefile
+++ b/clients/android/Makefile
@@ -32,6 +32,9 @@ installdebug:
install:
adb install -r app/build/outputs/apk/release/app-release.apk

+clean:
+ /bin/rm -fr ./app/build
+
test:
# TODO(mpl): can't run the instrumentation tests within docker, since
# can't connect to the phone from in there.