logd: klogd and Mediatek part deux

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

Bug: 23517551
Change-Id: I568e25c5aa6d8474835454a0e83b19c2921b7986
1 file changed
tree: 96e20999b05a55408d7e10fdccb08d913163ec08
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/