Enable -Wnon-virtual-dtor build warning

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177385 91177308-0d34-0410-b5e6-96231b3b80d8
The testing to ensure a vector of zeros of type floating point isn't misclassified as negative zero can be simplified, as pointed out by Duncan Sands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177386 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-symbolizer: flush internal caches functionality



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177390 91177308-0d34-0410-b5e6-96231b3b80d8