[MSVC] Turn C++ EH on my default

Our support for C++ EH is sufficiently good that it makes sense to
enable support for it out of the box.

While we are here, update the MSVCCompatibility doc.

llvm-svn: 261195
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 1599367..8441a91 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2410,11 +2410,9 @@
   }
 
   if (types::isCXX(InputType)) {
-    // Disable C++ EH by default on XCore, PS4, and MSVC.
-    // FIXME: Remove MSVC from this list once things work.
-    bool CXXExceptionsEnabled = Triple.getArch() != llvm::Triple::xcore &&
-                                !Triple.isPS4CPU() &&
-                                !Triple.isWindowsMSVCEnvironment();
+    // Disable C++ EH by default on XCore and PS4.
+    bool CXXExceptionsEnabled =
+        Triple.getArch() != llvm::Triple::xcore && !Triple.isPS4CPU();
     Arg *ExceptionArg = Args.getLastArg(
         options::OPT_fcxx_exceptions, options::OPT_fno_cxx_exceptions,
         options::OPT_fexceptions, options::OPT_fno_exceptions);