Rewrite DwarfSectionImpl::InsertFde

Simplify and fix the algorithm.

For consecutive functions (eg [10,20] [20,30]) without
padding in between, the old algorithm would drop FDEs.

Bug: http://b/150050915
Test: libunwindstack_test
Change-Id: Ie886922bec262fb64d4b2ecf01c2961d0652dcdb
(cherry picked from commit a6617cb17926a9868a900ce43c9b358bafe88d9b)
2 files changed