include/llvm/Object/ELF.h: do debug checks only when NDEBUG
validateSymbol() is called all over the place, and it seems it's a debug check.
It significantly speedups llvm-symbolizer used in tsan/asan/msan. validateSymbol() is the second hot function and accounts for 15% of runtime.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175192 91177308-0d34-0410-b5e6-96231b3b80d8