logd: klogd and Mediatek part deux

(cherry pick from commit 3de488e96694e2527114c84186260361bcec5f5c)

- switch to an open coded strnrchr
- validity checking on n, taglen and b values.

Bug: 23517551
Change-Id: I568e25c5aa6d8474835454a0e83b19c2921b7986
1 file changed
tree: 0d5788171392dd711e7bfa1183aff71731a8d51a
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/