liblog: suppress pmsg on user builds

(cherry pick from commit 7ef5249afacffe3901e3a602372c7d34cf655675)

- add optimized & cached LIBLOG_HIDDEN __android_log_is_debuggable()
- check when writing, either LOG_ID_SECURITY, SafetyNet or
  debuggable when pushing content to the pmsg buffer.

Bug: 27566046
Change-Id: I85f1b55ec329b38e00f4183836b6ed53046c323d
5 files changed