Partially reverts commit 436f5a031f.
Remove the variants taking a fully qualified LogSeverity. Instead
use a lambda with "using" statements to translate both qualified
and unqualified names into valid expressions.
Compile-time regression was measured as 0.1s for a thousand LOG
statements on a z840.
Update tests.
Bug: 31338270
Test: m
Test: mmma system/core/base && $ANDROID_HOST_OUT/nativetest64/libbase_test/libbase_test64
Change-Id: I36fdf30a9d535b19543307b85d1b3c19a97f20dd
1f5fb43047