Merge "libbinder: remove unused context variables" am: 280af8eb16 am: 3219ae64bc am: 65e60df3d2

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1416688

Change-Id: Ica6f2c9e5402dc2a0d57b9fb4d4722123585fcd9