Remove DeclareLocalVariable function

It wasn't providing anything. It would only return true, and all of the
other places in the file declaring local variables just used AddLiteral
with StringPrintf.

Test: atest aidl_integration_test && atest aidl_unittests
Change-Id: I4e8c08b26f829528eea57b159fee4fd828a19605
1 file changed