Don't re-export libbinder headers from libstagefright_foundation

The headers of libstagefright_foundation do not reference libbinder
headers. Therefore, the libbinder headers don't need to be re-exported.

As a good side effect, libbinder is no longer built for
com.android.media APEX where libstagefright_foundation is a member of.
Before this change, due to the re-export of headers, the media APEX
variant of libbinder had to be created.

Also, this is a partial cherry-pick of Ieb731a8112b1f3bdc6862059671e8a9dd31d88e1
from the internal master.

Bug: 147671264
Test: m
Merged-In: Id16054593487f042fba6e46b114da52439e98e07
(cherry picked from commit a959536b)
Change-Id: Id16054593487f042fba6e46b114da52439e98e07