Add a hidden API for EXTRA_LAST_KNOWN_NETWORK_COUNTRY

Test: Treehugger; atest
Bug: 152246523
Change-Id: Id77b81e18b293d8d8c8e7b3127826fbd577d6117
Merged-In: Id77b81e18b293d8d8c8e7b3127826fbd577d6117
(cherry picked from commit 8d1791efc788cf51984b9167f492488bd5deb996)
1 file changed