Remove some unused imports

git-svn-id: https://llvm.org/svn/llvm-project/lnt/trunk@210122 91177308-0d34-0410-b5e6-96231b3b80d8
Fixups in geomean calculation

Geomean calculation was having problems with compile test suite.  Fix that, as well as some bugs in how it was calculated.

git-svn-id: https://llvm.org/svn/llvm-project/lnt/trunk@210123 91177308-0d34-0410-b5e6-96231b3b80d8