[WebAssembly] Add WebAssembly to LLVM_ALL_TARGETS

Summary:
After fixing memory leaks in rL343362 and rL343733 the sanitizer builds are
clean and we should be good to build by default again.

Differential Revision: https://reviews.llvm.org/D52850

llvm-svn: 343746
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 22e22c8..3e7a9dd 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -287,6 +287,7 @@
   PowerPC
   Sparc
   SystemZ
+  WebAssembly
   X86
   XCore
   )