[PowerPC][NFC] Update build-vector-tests.ll using utils/update_llc_test_checks.py

build-vector-tests.ll is a huge testcase, it is hard to maintain: eg:
any fundamental changes might need to update hundreds of lines. We should
leverage the script to maintain it.

This patch simply run utils/update_llc_test_checks.py on it. There
should be no missing test points.

llvm-svn: 360175