Fix some llvm-gcc warnings in testcases, mostly by adding includes or adding

Fix some llvm-gcc warnings in testcases, mostly by adding includes or adding
declarations. These are the fixes that I was pretty confident about, there are
still a lot of other llvm-gcc warnings of which I'm not sure if they can be
safely ignored or fixed, without breaking the test case.

This fixes 11 testcases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52176 91177308-0d34-0410-b5e6-96231b3b80d8