ValueTracking.h Don't mark header functions as file-scope static

This creates ODR violations if the function is called from another inline                                                                   function in a header and also creates binary bloat from duplicate definitions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316476 91177308-0d34-0410-b5e6-96231b3b80d8