Add filegroup for supporting apache-http stubs generation.

Bug: b/70351683
Test: m clean && m check-apache-http-legacy-api,
and compare the old and new stubs.jar using md5sum.

Change-Id: I0035837aef48a76e40a2c723c2adce3ff129ad28
Merged-In: I0035837aef48a76e40a2c723c2adce3ff129ad28
1 file changed