Change-Id: I9f49970e5e06d1afd3fc066a20d1671c93e262fc

With gb_Jar_add_jar and gb_Jar_add_system_jar adding to the manifest
classpath automatically it is no longer necessary to call
gb_Jar_set_jarclasspath manually except for the URE jars, which
are apparently not supposed to be added automatically.

Change-Id: I1e743e7ecb9cb5651e02005aa09e127bea1b0a29

Naming convention for gbuild methods:
- "add" is used for stuff that is logically a part of the target
  (i.e. not registered at the Module, but defined in the target's makefile)
- "use" is used for stuff that is logically a different target
  (i.e. it is registered at the Module, has it's own makefile, may be
  in a different module than the target)

Add smoketest to tail_build and make it a subsequentcheck target.