Remove malloc/free for inline overlay values

Remove malloc/free of android::ResTable_entry for inline overlay
values.

Add `target_entry_inline` to the idmap format to encode inline overlay
values separate from direct mapping of target resource to overlay
resource. This reduces the number of bytes needed to represent a direct
mapping of target resource to overlay resource from 9 bytes to 8 bytes
per entry.

Fixed all idmap alignment issues that required the framework to use
"#pragma pack(push, 1)" when loading idmaps.

Bug: 170341022
Test: idmap2_tests and libandroidfw_tests
Change-Id: Iab4d3902508f02773464724913e0ee966e3689e4