Revert r252858: "[WebAssembly] Switch to MC for instruction printing."

It broke the CMake build:

"Cannot find source file: WebAssemblyRegNumbering.cpp"

llvm-svn: 252897
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
index acfd738..6aae5d3 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
@@ -41,11 +41,9 @@
 // currently.
 let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 in {
 def SWITCH_I32 : I<(outs), (ins I32:$index, variable_ops),
-                   [(WebAssemblyswitch I32:$index)],
-                   "switch $index">;
+                   [(WebAssemblyswitch I32:$index)]>;
 def SWITCH_I64 : I<(outs), (ins I64:$index, variable_ops),
-                   [(WebAssemblyswitch I64:$index)],
-                   "switch $index">;
+                   [(WebAssemblyswitch I64:$index)]>;
 } // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1
 
 // Placemarkers to indicate the start of a block or loop scope.