Add minApiLevel 30 argument to stats-log-api-gen

Add minApiLevel 30 argument to stats-log-api-gen to maintain backwards
compatibility with R in the next Android release.

Bug: 160938178
Test: m
Test: inspect generated MediaProviderStatsLog
Change-Id: Ib069157b6ad30d6ff30f846feacd69002bc2bc4d
1 file changed