Allow user add/remove broadcasts to manifest receivers

Bring the implemention into line with the documented (intended)
behavior.  Note that these broadcast already require that the recipient
hold a signature|privileged permission.

Bug: 177072348
Test: manual (bug test case validation)
Change-Id: Ic56892b934017f0d8f75c9c97932d4f6f2bc4166
1 file changed