[Docs][JIT] Update the clang++ invocation lines in the kaleidoscope docs.

The old examples had missing/incorrect flags that were causing failures on newer
versions of clang and the tutorial code.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221419 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unnecessary .c_str() when implicitly converting to Twine

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221422 91177308-0d34-0410-b5e6-96231b3b80d8