[WebAssembly] Add exception handling option

Summary: Add exception handling option to clang.

Reviewers: dschuff

Subscribers: jfb, sbc100, jgravelle-google, sunfish, cfe-commits

Differential Revision: https://reviews.llvm.org/D43681

llvm-svn: 326517
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index 595909e..0026f1f 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -2352,6 +2352,8 @@
 
 .. option:: -msimd128, -mno-simd128
 
+.. option:: -mexception-handling, -mno-exception-handling
+
 X86
 ---
 .. option:: -m3dnow, -mno-3dnow