[LLVMdev] [Windows] Cleaning up dialog box suppression code.

[Michael Spencer]

We have multiple different places where we handle dialog box
suppression to various degrees. I recently discovered another place we
need to do it, and so I wanted to unify all of them.

We currently have most of this suppression logic behind the
LLVM_DISABLE_CRASH_REPORT environment variable. I would like to make
it unconditional. I don't believe we have any users that desire the
dialog box behavior, as all of our tools are used via the command line
and can report crashes via stderr.

I wanted to check with other Windows users/vendors for exactly which
behavior they wanted.

The case where I need to add it now is the lto shared library. The CRT
crash reporting state doesn't seem to be replicated across DLL
boundaries, so the main application can't actually control this
currently. Should we unconditionally disable here? or add an API to
control it?

- Michael Spencer