Don't explicitly set LOCAL_JAVA_LANGUAGE_VERSION := 1.8

1.8 is now the default, so this is now redundant.
If and when the default language version changes to something
higher, libcore should also use that language version.

Bug: 38177569
Test: Treehugger

Change-Id: I9a1b5a37aeacd530d74ea2a3e5a29913b399cc2b
1 file changed