[PATCH] clang-cl: Map /EHs- to -fno-exceptions

[Hans Wennborg]

lgtm with a few comments

================
Comment at: lib/Driver/Tools.cpp:4409
@@ -4405,1 +4408,3 @@
 
+  // /EH controls the whether to run destructor cleanups when exceptions are
+  // thrown.  There are three modifiers:
----------------
nit: "the whether".

Also, do you think we should break this into a helper function?

And I suppose we should forward the /EH flag to msvc when invoking the fallback.

http://reviews.llvm.org/D4317