Fix unused DT entry warnings.

 DT_STRSZ Implement strtab boundary checks
 DT_FLAGS_1 Warn if flags other than DF_1_NOW|DF_1_GLOBAL are set

Bug: 17552334
Bug: 18186310

(cherry picked from commit 6cdeb5234d7f4523fe9d83974f265d80f10512a6)

Change-Id: I7ffc7bc600798308a77ad949a644949b64250ae2
4 files changed