Driver: Print the clang version and original command in crash scripts

When a crash report script doesn't work for a reproduction on your
machine for one reason or another, it can be really tricky to figure
out why not. The compiler version that crashed and the original
command line before stripping flags are very helpful when this comes
up.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@231989 91177308-0d34-0410-b5e6-96231b3b80d8