liblog: fixup log_id_t

1) We don't need two copies of log_id_t
2) We don't need misleading sizeof_log_id_t or typeof_log_id_t macros
3) logd should use android_log_header_t explicitly for its recv buffer
   size
4) Following on from b/129272512, we're settling that returning
   LOG_ID_MAX is an acceptable return value from
   android_name_to_log_id().

Bug: 129272512
Test: build, liblog, logcat unit tests
Change-Id: I67fb964a4a0ae9cb6e1514ca110e47e00dfcfa9a