A new bug was introduced in a80bdfd0 "Change sinpi_{1,2,3,4}_9 from
tran_high_t to int16_t". Reverted the change in this file.

BUG=webm:1450

Failed test C/TransHT.AccuracyCheck/26.

Change-Id: Id001f57aad811803ef7d367d2b2bc008d8499991