Link sigchain to surfaceflinger main executable

 And export necessary symbols to preempt calls from libart.so

Bug: 15345057
Bug: 15426766

(cherry picked from commit f3da24d8cf02d7c74ff7c24eae0154a21a192fda)

Change-Id: I03b632e0bf2cbaf4a0e68cd0af4e991f7f6b08e4
2 files changed