Add Gradle build support

(Direct cherrypick of Justin's CL from calculator tree.)

Test: ./gradlew :cr:build
Change-Id: I518e41bbd7e0d0f4195af80f882a1feef86a662e
1 file changed
tree: fd611cad36e544564269e1901007b0aa0027a700
  1. src/
  2. tests/
  3. Android.mk
  4. build.gradle
  5. COPYRIGHT.txt
  6. impl.html